View photos of the edible plant Calochortus nuttallii (Sego lily), profiled in the Wild Edible Series: Colorado, Montana, Nevada, South Dakota, and Utah.

A passage from Wild Edible Plants of Colorado:

Be sure the population at hand is abundant – two species in southwestern Colorado are at their range’s edge (Calochortus flexuosus and C. aureus). All species are only identifiable for 2–4 weeks when it is in flower/seed. After this window has passed, its above–ground trace is gone until next year.