Bombus californicus browsing on a sage blossom for nectar. Note her extended tongue and lack of pollen on her hind legs. Note also that this species of bumble bee has no yellow hairs on their faces nor the top of the head, unlike the other common bumble bees in this area.
The plant looks like black sage, Salvia mellifera, but it could be another species, cultivar or hybrid.
There are two photos of the same bee in this upload.