Mary Meyer's blog GrassTalk is all about ornamental and native grasses.
Ornamental Grasses for Cold Climates helps northern gardeners select ecologically beneficial grasses for lawn or garden. The newest edition includes a map of the USDA's updated 2012 plant hardiness zones, more than 100 perennial and 35 annual grass species, and more than 100 color photos. It is based on 25 years of research by Extension horticulturalist Mary Hockenberry Meyer.
The grass collection at the MN Landscape Arboretum is one of the largest in the Unted States with over 200 native and ornamental species and cultivars.
The Minnesota DNR has a section on their website that lists all the native garden centers in the state.