Looks like one of the lettuces. Pull out by hand, digging the root when small if you don't want to use herbicides. You can add 2"-3" of mulch to the veggie bed after removing the weeds which will help keep them away.

Your grass looks very patchy, so the exposed soil is giving the weed seeds a good start. Try to improve the grass with topdressing and fertilizer. Or, if a bad place for grass, replace your lawn with a flowerbed using the newspaper method of grass killing.

Check out this wedb site
http://www.turf.uiuc.edu/weed_web/index.htm

It looks like "Curly dock or curled dock" to me.

I would say perennial sowthistle.

Here is a pic of curly dock from WildmanSteve's website.

http://www.wildmanstevebrill.com/Clippings.folder/EdiblesInThePark.html#Anchor-CURLY-11481

It doesn't look quite like your weed, but I did 'identify' (find) that weed recently (just forgot its name). I also think it's one of the wild lettuces.

Here's a pic of prickly sowthistle
http://www.countrylovers.co.uk/wildfoodjj/psowt100.htm
and here's smooth sowthistle:
http://www.countrylovers.co.uk/wildfoodjj/sowth100.htm
Also a little different from your weed, I think.

Omigod! I just realized where I'd seen your weed before, ninjapixie. It's growing all over my yard! And I've been trying to find out what it is.

Your photo does not show the flowers, which are very distinctive (if your weed is, indeed, mine). But the leaves and their patterning are identical.

The distinctive thing about this weed, if you don't keep it mowed or pulled, is that it keeps putting out these one-day yellow blossoms that look a lot like morning glory flowers. It becomes very leggy if not topped, with each new day's set of flowers being higher on the stalk than the ones from the day before. If you do pinch off the top cluster of buds, the plant will bush out, producing lateral branchings with more flowers.

As a wildflower, this one is vividly colored and kind of pretty. The down side, even if you pinch it off to make it a bushier plant, is that you end up with these droopy dead flowers every day, as the new blossoms open.

It has a tap root, but if you pull the plants when the soil is wet, most of it will come up.

I would love to know the name of this weed, too. And I'm curious if it's edible or has any medicinal properties, since it does look like it's related to chicory or wild lettuce or the thistles.

Genie

One other thing about this weed/wildflower. The flowers open early in the morning and prefer cooler temperatures. Thes flowers look like big, brilliant, beautiful yellow morning glories during the morning hours, but they wilt quickly in the heat of the day.

I don't think there's any way of makin this plant 'behave' - i.e., stay and reseed itself in a designated garden spot. If you could, they'd probably be well worth keeping.

I found it! I was browsing some "weed" and "wildflower" pics and came across the exact image of my yellow wildflower plants!

I am almost certain this is what your "weeds" are, Ninja. At least the leaves look exactly like my oenothera glazioviana/evening primrose plants do before they flower.

Some varieties have evening-opening blossoms (hence the name) and others (like mine) have blossoms that open in the wee hours of the morning.
Mine certainly behave like weeds, in that they take root wherever they darn well please. But that doesn't mean they won't also sprout in designated areas if you plant the seeds there. (You just have to pull up the ones that aren't behaving.)

Here are a couple more images:
oenothera (Evening Primrose) Glazioviana

oenothera glazioviana images (Google)

Oenothera Biennis

info on medicinal/nutritional uses of evening primrose (oenothera biennis)

Here is what my oenothera biennis plants look like shortly before they first bloom: But before they get this tall and leafed out, when they first sprout up on my lawn, they look exactly like the pics in your first post, Ninja.

Genie

Genie, the yellow ones that open in the day are also called sundrops.

I have the tall wild ones that just started blooming, and some shorter tame ones that bloom end of May/early June. The tame ones (don't know the variety, my neighbor gave them to me) have better looking foliage, but they spread pretty good too.

Ninjapixie's are something else. I get those too, but pull them out. I thought they were something from birdseed.

jrstark, I based my "diagnosis" on just the leaves, since ninjapixie's photo did not show the flowers or the plant in later stages. I know that many plants have almost identical-looking leaves. But my wild evening primroses (which I've discovered DO open up late in the evening, when it cools down) look [i]exactly[/i] like ninjapixie's at that stage of development.

Ninja, I'm wondering if you let any of yours live long enough to find out what the flowers are like. That would help identify them.

I haven't checked in here in a couple of months -- my apologies for the late reply.

First off, thank you so much for sharing your research, genie_wilde! I'm glad you were able to identify your plant!

Unfortunately, the one I posted about isn't evening primrose. (I do indeed like that one, though -- I have a bunch of the small, well-behaved version. It multiples like crazy, which isn't a problem for us so far.)

My weed looks a bit thistle-ish as it gets older, and shoots up a central stalk three or four feet tall to pop yellow flowers that look a lot like dandelions. They turn to fluff and float away in the wind.

I think a better mulch job will control this guy in the flowerbeds, and our grass is starting to crowd it out -- so hopefully that'll work in the long term. What a pain this weed has been... :)

Judy B. nailed when she said it was one of the lettuces. If you have lettuce that you have not culled did up the root. Dock's normally have a fleshy non-pointed leaf. This type of lettuce is part of the endive section of the family. Next year just for fun plant one of the 10 cent packages of leaf lettuce and let it go to seed.