View photos of the edible plant Achnatherum hymenoides [Oryzopsis hymenoides], Indian rice grass profiled in Wild Edible Plants of New Mexico and Wild Edible Plants of Arizona.

A passage from Wild Edible Plants of New Mexico:

Before corn arrived on the scene, the plant was a main grain staple of the western Indians. The plant’s commonality and seed size (for a native grass, it’s one of the largest) made it a valuable and much utilized edible.

A passage from Wild Edible Plants of Arizona:

A native bunch–grass common to the Mountain West, in Arizona, Indian rice grass is concentrated in the northern part of the state, particularly on the high plateaus (Colorado/Kaibab). Foragers looking south of Prescott–Sedona–Mogollon Rim will likely be disappointed.