It looks very much like a plum tree. Depending on where you are in Sacramento, your house was built over an old orchard.
We lived in Rancho Cordova when I was in 3rd and 4th grade (military family), and there was still an orchard at the end of the street and an empty field across the street where there are now a community college and a high school.
I make plum chutney and Chinese-style plum sauce regularly, since my MIL's next-door neighbor has a plum tree.
And, of course, when we visit during plum season (July and early August in Palo Alto), there's the requisite amount of eating plums over the kitchen sink!
Sunset Zone 17, USDA Zone 9