Supplier of native plants/grasses
Some Native Plant suppliers that come to mind are:
Minnesota Native Landscapes
Most of these are outside the immediate metro area. Most all will ship. Glacial Ridge will deliver your order to the St. Paul Farmers’ Market. I believe they have a booth there.
You might keep an eye out for local native sales. I know Burnsville is having a native Plant Sale on May 18th from 9-12 at the Burnsville City Center. The sale is open to the public.
Most major Garden Centers (Gerten's, Bachmann's, etc.) usually carry some native plants.