Prairie Moon Nursery in Winona, Minnesota. They have a great catalog, lots of color, and gardening tips.

Prairie Nursery in Wisconsin. Seeds (forbs and grasses), as well as plants. Natives only, and an excellent, informative catalog.

Note that 'wildflower' doesn't have a well-defined meaning. It can refer to native forbs (nonwoody flowering plants) as well as to weeds. And in nature, forbs never grow without grasses, which act as a sort of matrix to hold the soil and support the flowers' roots and tall stems. What you are looking for is prairie plants, both grasses and forbs.

Here is a link that might be useful: Prairie Nursery

Eric and Elaine,

Thank you so much for the information.