A passage from Wild Edible Plants of Arizona:
It is abundant from the White Mountains and Mogollon Rim to the San Francisco Peaks and Kaibab Plateau. Pinyon and Ponderosa pine elevations are its preferred associations.
A passage from Wild Edible Plants of New Mexico:
Ripening mid to late summer, the purple fruit are eaten raw. They are seed–filled, but if found in optimal condition, are still sweet and juicy.
A passage Wild Edible Plants of California::
Serviceberry seeds, like most of the Rose family, contain traces of cyanogenic glycosides. Drying/heating destroys these compounds. But even fresh in moderate quantities there is little to fear from Serviceberry seed. There are no cautions for the fleshy portion of the fruit.