I saw a couple of these circling around in a grassy area near the Bay. I think they have nests in the ground; I had sat down in the grass, plopped my backpack beside me, and I think I disturbed their landmarks; they kept hovering around the grasses near me, landing occasionally, then taking off; eventually they climbed down into the grass, and I didn't see them again.

Edit:
BTW, these are somewhat larger than a normal honey bee (A. mellifera), maybe 1" total length.