That I can think of, which may be Native to Kansas (please, double check me):
Sand Cherry, Arkansas Wild
Rose, Gooseberry, some species of Goji Berry (you'll have to look this up, but apparently there are several species native to US & Mexico, I just have no idea what yours is. Honestly, look for it under Wolf berry or Silver berry, but there is crossover in names with the latter), Buffalo Gourd (be careful where you get it from. in some places, this plant is edible & in others it's not. We're still not sure if it's different strains/ species, or the environment itself, so don't source it from Arizona & expect to be able to eat it. If you can find it locally, you should be fine), Prickly Pear Cactus, Wild Rice, some species of Groundcherry, Dewberry, some species of Serviceberry, Wild Kidney Bean, Camas, Bergamot, Blueberry, maybe some species related to Canadian Lily, some native ferns are edible, elderberry,
honey locust, Osage orange, I'm sure you have at least one species of wild onion, possibly currants, sumac, American Wintergreen, Prairie Potato
I've been cataloguing wild native foods from across North America, but not a whole lot of regional specifics outside of my home region. Definitely not Great Plains, as there's a lot of crossover. Most of the diversity there comes from unique species of the same kinds of plants, rather than entirely new plants, though there are one or two I've been made aware of.