Golden bean, Thermopsis rhombifolia, is a cheerful yellow sight on sunny, lower elevation hikes.  This is another species that seems to have too many names to keep track of.  It is also called golden banner, buffalo bean, golden pea, wet tooth, yellow bean, false lupine, prairie buckbean, buffalo flower, or yellow pea.

This is the thermopsis species of the prairie, which is smaller and grows in drier environments than the mountian thermopsis (Thermopsis montana or mountain goldenbanner).  I have found golden bean in similar elevations to mountain golden banner, but golden bean usually arrives earlier in the year and is not anywhere near as tall and lush.