Prairie Moon Nursery in southeastern Minnesota is an excellent source for a huge variety of wildflower seed (and plants).
http://www.prairiemoon.com/
Many nurseries sell wildflowers to one degree or another, but two really good ones that specialize in them and are in your area are :
Shooting Star Nursery in Kentucky
http://shootingstarnursery.com...
and Sunlight Gardens in Tennessee
http://www.sunlightgardens.com...
