Well, what is rare for where I am might be pretty laughable for some places even a county or so away, but, with you living in Chicago, you've probably in a similar predicament.
So far, what I've gathered together are:
--Allegheny Plum @ (I think you guys would have a different species of wild plum, though)
--American Cranberrybush Viburnum/ Highbush Cranberry*
--American Spikenard*
--Atlantic Camas/ Wild Hyacinth*
--Beech (self harvested)
--Blueberry@
--Buttonbush@
--Eastern Red Columbine*
--Eastern Sweetshrub/ Carolina Allspice$
--Black Elderberry*
--Red Elderberry*
--Fire Pink*
--Fringed Bleeding Heart/ Turkey Corn $ +
--Great White Trillium*
--Illinois Rose*
--Indian Paintbrush*
--Ohio Buckeye (self harvested)
--Red Puccoon/ Bloodroot$
--Scarlet Bergamot/ Oswego Tea+
--Smooth Solomon's Seal*
--Wapato/ Duck Potato*
--American Wintergreen+
--American Hophornbeam (self harvested)
--Black Cherry✓
--Black Chokeberry✓
--Black Tupelo✓
--Cardinal Flower*
--Celendine Poppy*
--Common Hop✓
--Wild Cranberry✓
--Cream Gentian*
--Downy
Wood Mint*
--False Indigo Bush*
--Goat's Rue/ Rabbit Pea*
--Honey Locust✓
--Jack in the Pulpit/ Indian Turnip*
--New Jersey Tea/ Snowball Bush*
--Purplestem Angelica*
--Ramps*
--Serviceberry (self harvested)
--Steeplebush*
--Strawberry Blite*
--Virginia Persimmon✓
--Wafer Ash/ Hoptree*
--Wild Cucumber*
--Wild Ginger*
--Wild Kidney Bean*
--Wild Trailing Bean*
* = Prairie Moon Nursery
$ = Seedville USA
+ = Outsidepride
✓ = Hobbyseed
@ = Amazon, third party
I was also hoping to get Kentucky Coffeetree, Yellowwood Tree, Inkberry Holly/ Appalachian Tea, Winterberry Holly, American Lotus, Indian Potato/ Groundnut/ Hopniss, Hogpeanut, Starflower, Papaw, Ghost Flower, Northern Bayberry, American Butterfly
Pea, the Eastern variety of Sand Cherry & a bunch more wildflowers over the next couple of years.
What I do already have a lot of here is Spicebush, Bigtooth Aspen, Basswood, several species of Maple, Elm, Fern, Oak &
Ash, Butternut, Sassafras, Trumpet Honeysuckle, Canada Sanicle, Jewelweed, Ironweed, Black Raspberry, Dewberry, Strawberry, Mulberry, Chokecherry, Pokeweed, Elkhorn Sumac, Cutleaf Toothwort, Bellwort, Springbeauty, Wild Geranium, Nannyberry, Mayapple, Catalpa & a bunch of invasives. There are a few rare plants I've identified, like Musquash
Root, but I'm hoping to bring in just as many, if not more species & take out as much of about six invasive plants that are really pissing me off as I can.
With edible foods, I was also putting together another
thread called "Edible Plants of the Continental US," on which I've managed to assemble quite a lot. So far, I think I have about 130 native plants from the Great Lakes region & just as many from across the rest of the country too. So, that's probably including all the plants that were common in our ancestors diets, at this point. Chicago is also a great spot for Plains plants.