Yellowbells, a native lily species, has been added to the USWildflowers database (06/28/2010.)  Scientific name is Fritillaria pudica.  This plant also is known by the common namesYellow Fritillary, Yellow Missionbells,  Gold Bell.  Photo below was taken Boise National Forest near Boise, Idaho on 06/08/2010.

Yellowbells - Fritillaria pudica