I live in northern MN by the Mississippi, and am looking forward to restoring a riverbank at a local park, what are some rarer natives that would help to truly restore the area to what it must have looked like before the 1700's?

Its a sandy site that has had knapweed and other invasives that have been removed. So far the only natives I've seen at the site that I didnt put in are willow, Vurgina creeper, common milkweed, golden rod, aster and four oclock. I have planted big blue stem, coneflowers, purple prarie clover, blanketflower, ect.

I live in St. paul and have benefited greatly from Mississippi market native plant sale but do you guys also know of any native plant dealers or nurshies other then highland that carry natives in my area?.