View photos of the edible plant Panicum hirticaule (Mexican panicgrass), profiled in Wild Edible Plants of Arizona and Wild Edible Plants of New Mexico.

A passage from Wild Edible Plants of Arizona:

Snip the entire panicle (with 2”–3” of stem) from the grass in late August – too soon and the seeds will not be mature; too late and they will have fallen. Place the panicles in a paper bag and set them aside for about a week. Strip the seeds from the stems by pinching low on the bunch and pulling towards the top.

A passage from Wild Edible Plants of New Mexico:

Compared to Indian ricegrass, the seeds are easy to process (but much smaller). Enjoy the whole seed (crunchy–mildly nutty) solo, or sprinkled on salads, meat, etc. They too are fine for flour/meal/gruel/sun–dried cakes. Nutritious, they contain, good amounts of protein, carbohydrates, and fats.