Non-Edible Plants in the Grassland
Stinging Nettle
The plant has many hollow stinging hairs on it's leaves and stems.
Milkweed
The Milkweeds other stuff is edible but it's sap contains poisonous chemicals.
Dogbane
Hemp dogbane, a poisonous herb, is found throughout the United States, including the western range states. The hemp portion of its common name comes from the fact that Indians used fiber from the bark for making rope.