Extremely good native plants abound there, as Scott so eloquently pointed out. In a low, sandy meadow I found the following good things, among many others. The first, Blue Hearts, is noteworthy for being the plant that brought together two botanical legends, Floyd Swink and Julian Steyermark. You can read about them here and here.
Buchnera americana (Blue Hearts)
Bromus kalmii (Prairie Brome)