Edible Wild Plants of the Prairie: An Ethnobotanical Guide
This is one of Sam Thayer's favorite foraging books, having read it cover to cover at least 30 times.
The Plains Indians found medicinal value in more than two hundred species of native prairie plants. Unfortunately, modern American culture has not paid much attention.
But in both the number of species used and the varieties of treatments administered, Indians were far more proficient than white settlers. Their familiarity with the plants of the prairie was comprehensive there probably were Indian names for all prairie plants, and they recognized more varieties of some species than scientists do today. Their knowledge was refined and exact enough that they could successfully administer medicinal doses of plants that are poisonous. All of the species used by frontier doctors were used first by Indians.