She was owned at various points in Georgia, South Carolina, Mississippi, and Arkansas. The precise sequence is not fully established. What is documented is that by sometime around 1840, possibly as early as 1831 by some accounts, she had come into the ownership of Robert Mays Smith, known as Robert Marion Smith, and his wife Rebecca Dorn Smith, a Mississippi couple who would eventually carry her across the continent.
Smith was a plantation owner from Mississippi. His household had the structure typical of wealthy Southern families of the period: enslaved people did the domestic, agricultural, and skilled labor. Among the skills Biddy Mason acquired — or possibly came to Smith with already — was midwifery. She had learned herbal medicine and obstetric care from other enslaved women, and her ability to assist with childbirth was a skill that was both deeply practical and, in the hands of an enslaved person, entirely at her enslaver’s disposal.
She had three daughters. Their names were Ellen, born around 1838, Ann, born around 1844, and Harriet, born around 1847. The identities of their fathers are not established in the historical record. Some historians have noted that Smith may have fathered at least one of her children; this is a possibility that the evidence does not confirm or rule out, and the prompt for this article appropriately classifies it as an unresolved question. The three daughters walked west with their mother, and their fate became bound up with hers in ways that would eventually shape two generations of the city of Los Angeles.