McFayden
Eternal Seed
Vesey
Thompson & Morgan
Richter's Herbs

Here's some online catalogs:
http://www.prairiehabitats.com/seeds.html
http://www.wildflowerfarm.com/
http://www.dominion-seed-house.com/e...x.aspx?CatID=9
http://www.holesonline.com/ordermail.asp
http://www.oscseeds.com/