Sugarhill, I order seeds regularly.
I order from various places that are well known and expensive, like T&M and Parks and sometimes I don't get the best germination.
I really like a mail order (no online) only place called The Fragrant Path. You need to send $2 for their paper catalog (descriptions only. Descriptions are fairly accurate and I look up photos on the web). Once you buy seed from them, they will send you another catalog the next year:
The Fragrant Path
P. O. Box 328
Fort Calhoun, Nebraska 68023

I have wonderful germination from JL Hudson, Seedsman.

Both of these companies are on the west coast, so some of the plants described are not as great for our climate, or have shorter or different seasons than listed.

Pinetree Gardens has good basics. Cheap.

Secret Seeds in the UK is expensive, but excellent.
Patrick Studio Seeds in Canada is also very good. Nice selection of perennials.
I buy annuals from Wildseed Farms and have the best germination rates ever from them!
Everything I bought at Seedhunt did very, very well.
Selected Seeds is great for things you can't find elsewhere. Often oldfashioned strains of plants.
I'm going to try buying native plant seed from here this year:http://www.easywildflowers.com/Seeds.htm
I ordered Herb Seeds from The Thyme Garden last year and grew some really cool and unusual things. http://www.thymegarden.com/site/561124/page/219920

Is there anything in particular you are looking for? I have oodles of seed. I often grow only one variety of a plant at a time (this time for example, whites like white nigella) so that I have a true strain and lots of seed. Let me know, I may have some things you might like.

GGG

Thanks for all the great info, GGG. I had a chance to look at a couple of the sights last night. What a treasure trove.

I'm not looking for any seeds that I thought would be unusual, but codonopsis seeds have been hard to find. I never would have thought that. I want some more columbine seeds - don't know which ones yet. And I'm looking for creeping oregano. Let me look through all the nurseries you posted, and if there is something I want that I can't find, I'll take you up on your offer. Winter sowing was so easy that I want to do it again this year.

I do know one thing I haven't found anywhere - some old-fashioned scented petunias. I know people used to grow those with success in the South, but could only find one place with seeds and they were sold out. Don't care about the color - just want scent and survival.

Sugarhill, the Barbara Bush petunias that Wildseed Farms carries have a scent, and they are a cross between old fashioned types so the color is more saturated, but they do great in heat. Best petunias I've grown, especially directly in the ground.
Rare codonopsis seed can be obtained from Wales, but it's hard to find the exact time they stock it...everyone wants to buy some! I should think this year that a few other places will have it. A german place also sells rare seed. Please email me, I can try and send you my entire seed link file.

GGG

GGG, I just looked at your seed trade list on your page for the first time and that curly rush "afro" is sooooo cool..

Sugarhill, I try to not order too many seeds but placed a large order last winter with Harris Seeds www.harrisseeds.com and was very pleased with everything I got from them. I ordered from the "grower's catalog" or something like that. You have to buy more seeds than you'd probably want by going that way, but some of what I purchased was cheaper than from their retail catalog, and I got more seeds than I would have from the retail.

I am an Ebay addict, but have never ordered seeds from anyone there, so can't really recommend anyone. I did do a quick search though for the old fashoned petunias that you're looking for and found a seller with 660+ seeds for $1.50 + $1.50 shipping...Might be worth a try for that price!

I order many seeds from eBay, and unfortunately my best seed person has gone astray and is no longer able to sell. Bummer. Wildflower, you can't put the rush in the ground, it's too invasive but it is great in a pot. I wrap the pot in a plastic bag to hold in moisture. You may surely have some seed. It's simple to WS and germination is high.

GGG

Select Seeds has scented petunias. They even have an heirloom climbing petunia.
Select Seeds/Antique Flowers
180 Stickney Hill Road
Union, CT 06076-4617

Here is a link that might be useful: Select Seeds/Antique Flowers