California Towhee
In this case, it's likely 'Barbara The Builder' because this is a California Towhee and for this species, the female is in charge of gathering materials to build the nest while the male watches over their territory. These birds are common in the Sacramento region year-round and very tolerant of nosy photographers compared to other birds in the area. This one was hopping up the trail towards me and I watched in amazement as she carefully and stuffed more and more dried grass into her mouth before she flew up into a tree to continue her home improvement project.