MSU Extension does not offer a free seed program. However, many local libraries in Wayne County have "seed libraries" that allow you to pick up seeds donated by the community. I know that Plymouth, Livonia, Riverview, Trenton, and Westland, public libraries all have seed lending programs. It looks like the Detroit Public Library branches also have free seeds until they run out. 

If you live in Detroit, Keep Growing Detroit is a fantastic organization, sharing a lot of knowledge and plants. Check out their Garden Resource Program for plants and their classes and workshops.