Wait a minute. If you are as old as I am, your great-grandmother lived in the latter half of the 19th Century. Chattel slavery had already been ended. If your Great-Grandmother was a Paiute/Shoshone she wasn’t originally from the San Francisco Bay area; at that time the Utes/Paiutes/Shoshone lived well to the East, in the Great Basin of Utah, Nevada, and contiguous areas. Some bands might have lived in the Mohave; that would be in California, but a long way from the Bay Area. She might have been taken from her family/people (by whom? Under what circumstances?) but “placed in servitude”? Again, by whom? What would have been the terms of this servitude? Who were the Berryessa Family?
If you will pardon my saying so, your account sounds like a family tradition originated by a young woman who didn’t have a clear idea what was happening to her, or why, only that she was no longer with her family and instead was in a household of strangers who treated her like a servant. The plot of Cinderella, but without the Prince or the glass slipper. Or like one of the stories of the kids from the “Orphan Trains.”
Part of my own family’s oral tradition concerns my Irish Grandmother. She was from an upper-middle class family in Belfast. For reasons we don’t like to talk about, she emigrated to the US, where she found employment as a maid in a hotel. At one point, her mail got mixed up with a guest’s. She was summoned to the guest’s room; the other woman turned out to be *her own step-sister* from Belfast. Neither of them would acknowlege by word or gesture that they knew and were related to each other. They exchanged the misdirected letters, and parted without further contacts. EVER. Relationships between household and domestic staff were harsh sometimes, in those days. And could be confusing and confounding.
What geography her people originated from is hard to determine, due to the fact that natives didn't receive a lot of consideration and were not important in the eyes of the Spanish or the American settlers.