rose campion, malva (zebrina), violets, poppies
I am sure more will come to mind, so I may be back :)

Cosmos, zinnias.

Scratch that. I read seed easily instead of reseed.

Nigella, Kiss Me Over the Garden Gate, Fennel, Dill, Rudbeckia, Foxgloves, and Persicaria Painter's Palette.

Amaranth, paludosum daisies, california poppies, larkspur, red flax.

jacob's ladder reseeds everywhere in my garden as does bleeding heart.

I always smile when I see these for sale in garden centers because I know I'll be digging them out and giving/throwing them away.

see here's one I forgot :)

peach-leafed bellflower

sweet william

agastache
amaranthus

Echinacea, Helianthus Summer Sun, Verbena on-a-stick.

Start with one, wind up with lots and lots.

ageratum (Eupatorium coelestinum)
cornflowers
gaillardia
blue flax
pink linaria 'Canon J. Went'
amsonia hubrichtii
vitex (tree)
buddleia 'Royal Red'

Nicotiana and cleome, too. I have been working out of town for 7 years doing very minimal gardening and there they are to greet me this year. Clary sage used to be great for me, too - it finally is gone, but it was so kewl and did reseed.

I have others already mentioned here - nigella, larkspur, columbine, rudbeckia hirta, parsley. Tomatoes in the vegetable garden, too!

And I hit enter but nasturtium and morning glory reseed for me, too. I find petunias coming back up in pots or around the edges of the flower garden.

I, too, have rose campion that does really well - such a lovely thing that fills in for that vivid deep magenta between the spring peonies and the early summer daylilies. :)

Feverfew

Verbascum, Lunaria Annua (Honesty, Money Plant), Silene, Alyssum

Pulmonaria

Hollyhocks - and am adding cosmos and zinnia back to the list. Black and blue sage reseeds as well.

add to all of the above

oxalis
crepe myrtles
violas - love my reseeders
violets
hardy begonia
hellebores
black eyed susans
datura (moonflower)
salvia
parsley
.......

Lynne

Many of mine have already been listed and some of them I always wish I had dead-headed more thoroughly (shastas and feverfew especially). The peony poppies, forget-me-nots, and johnny jump-ups are my very favorite self-seeders and I never get enough so should seed more.

For me in the South, the best re-seeders are larkspurs, zinnias, Autumn Beauty sunflowers, nigella, Grandpa Ott morning glories, tithonias, portulaca, vinca, four o'clocks, and cosmos.

I don't think anyone said lupine -- as in Miss Rumphius. Also morning glories.

Here in my southwest Missouri garden the list is as follows:

Most all salvias
melampodium
ageratum
zinnia
marigolds
poppies
larkspur
snow on the mountain
kiss me over the garden gate
nigella
rudbeckias
heliopsis
feverfew
Four o'clocks
petunias
gaillardias
bronze fennel
dills
Jewels of Opar
vinca
globe amaranth
cosmos
cleomes

lavenders. I found several seedlings in my yard.
Lady's mantel
cornflowers
coneflowers
phlox (mine gave many seedlings)
russian sages

I think the only one I can think of that hasn't been mentioned is nepeta (the short one). That thing self-seeds like crazy! Also, geraniums - but the seedlings haven't bloomed yet, so I don't know if they came true.

Also, I have or had cosmos, larkspur, echinacea, blue flax, nasturtium, violas. My bleeding heart hasn't self-seeded - yet.

marsh mallow
morning glory
echinacea
rudbekia

Salvia coccinea reseeds especially well.
So does cypress vine, but once you have it, it is hard to get rid of.

monarda and yarrow.

Well, Glenda posted all of mine and other people posted Salvias and the others that reseed for me....hmmmm

Ah, Rose of Sharon. It's a shrub, but it reseeds easily here in Okie. I have little volunteers under mine this year.

I California, Mother had Geraniums that came up as volunteers, all varieties. How about California poppies and Statice for a sunny garden area.

Passionflower vine (Maypops) and Bittersweet vine - both.

Cannas (if you let them go to seed)
Pentas (not as easily here, but it does0
Gerbera Daisies (ditto)
African Daisies (ditto)
Painted Daisies (ditto)
Coreopsis
Ageratum (all kinds)
Irises (if you let them go to seed)
Daylilies (ditto)
Perilla (can become a pest)
Coleus
Forget-Me-Nots
Violets
Pansies
Violas (including Johnny-Jump-Ups)
Cat's Whiskers (in the South) I LOVE THESE!
Cleome (big time)
Vinca (Periwinkles)
Joe Pye Weed (All plants in this family are big reseeders.)
Butterfly weeds (Asclepias)
Thistles
Sweet Annie (Artemesia annua)
Silver Kng Artemesia (pretty for wreaths but invasive roots)
English Daisies
Snow-in-the summer
Ice Plant, Rose Moss and all other succulents self-seed
German Chamomile
Chives (big time)
Also, Jimsonweed is a BIG self-seeder. (AKA Devil's Trumpets).

Did anyone mention Foxgloves? I read through three times and didn't see it.

It just depends upon your soil and the region you live in too.

~Annie

Here's a unique one I love in and around my vegetable garden.....Borage. Attracts tons of bees and supposidly keeps the nasty horned tomato worms away!

My reseeders are feverfew, betony, hyssop, foxgloves, and my very favorite brunnera. As long as we are talking about reseeders, I have a question: I bought some plants this year from Annie's Annuals, so a little pricey, and some of them were annuals which I don't normally buy, but I purposefully bought plants that it said were easy reseeders, so I hope to see them all again. Is there anything to do to encourage reseeding? Like, I noticed this year, I have basically no reseeding, and I am wondering why that is (so as to make sure I don't repeat it next year with these annuals!). It was a particularly hot, dry summer last year so that is one variable. Also, I mulched heavily for the first time ever. Don't know if either of those things had anything to do with it. Any advice on how to encourage reseeding would be appreciated!

MilaB, heavy mulching will eliminate much of the self-seeding altho not all. Last year I removed most of my self seeders and mulched heavily but some seedlings have come up. I've been weeding out lots of feverfew this spring, that plant is very persistent. If you push back mulch in places and scatter seeds on the soil they'll grow.

Most of my reseeders have been listed altho I didn't see Iceland poppies. I don't have many left as they mostly get mowed or maybe the horses eat them in my outer yard.

While some reseeders can be good it's too easy for a garden to turn into a jungle! Don't ask me how I know this! LOL I'm not letting them take over again.

This spring I found 3 tiny plants that look like catmint and the only catmint I have is Walker's Low. Does this plant reseed? I had read the seeds are sterile so didn't expect seedlings. Anyone else have this plant self-seed?

I've also had liatris,yellow scabiosa,wild ginger, and sanvitalia along with lots of those all ready mentioned. Forget me nots would be my favorite. :)

Marlene

knaytia, scabious, pulsatilla (to my joy), achillea, alliums (various) corncockles, cardamine, ursinia, layia, mallows (all types), valerian (annoyingly), cerinthe, sunflowers, species tulips, geum rivale, geum chiloense, campanula rotundifolia (and various others), petrohagia, many hardy geraniums,

luckygal, I had a thought about your reproducing catmints. This spring, I was pinching back some catmint plants, and left the little tips scattered on the ground. And darned if they aren't trying to turn themselves into new little plants! They are definitely still very green weeks later, and turned themselves upright.

MilaB, the small plants I found might have come from deadhead cuttings I didn't clean up well, I'll never know. If so I may strew some around this year and see what happens! Two years ago in the spring I deliberately took many cuttings from the Walker's Low Catmint I had bought as a small plant the year before. I used rooting compound and stuck them into pots of good potting soil. Despite my neglect over the summer many survived and are now fairly large plants. So I think you will have more plants from those cuttings.

This year I've found a few delphinium babies that are obviously from seeds. Have moved them to other areas and hope they survive. I also always have lots of Columbine, Lamb's Ears, and Jacob's Ladder plants from self-seeding. I seldom dead-head those as want more Columbine and Jacob's Ladder and the bees love the Lamb's Ears so much I can't bear to remove them. I just give away or throw away extras.

I have a small (1 1/2 in across) delicate bell shaped flower about 6-8 in tall usually in pink to salmon shades that reseeds itself. It does not seem to be mentioned here, I've known the name, but can't remember it. I'm giving some seeds to a friend and would like to tell her the name. It's not a real popular name. Can you help?

Can you give us a location? Or even better, a picture?

I finally found the name on Ed Hume seeds sight...it is Godetia, they easily reseed themselves. I can send them on to a friend, now knowing. Love the plant and flowers. THANKS

Here in my zone 5 garden: Laura Bush petunias, larkspur, nicotiana, rudbeckia, agastache, feverfew, scabiosa, shasta daisies, catmint, lamb's ear, clary sage, solidago, hollyhock, ladies mantle, perennial geranium, coneflowers, helianthus lemon queen, joe pye weed, asters, phlox, poppies, sweet william, allium, daffodils, monarda, yarrow and hardy mums like clara curtis. I'm sure I've forgotten a few...