Mary C. Ferguson (maiden name: Chalmers) was born on September 5, 1842, in Alabama to James and Eliza Chalmers. Her father was a merchant who owned $18,000 of real estate and $88,000 of personal property by 1860. She grew up and attended school in Pickensville, Alabama.
She married William A. Ferguson in the early 1860s, and they had at least seven children: Mary, born around 1862; William, born around 1873; Chalmers, born around 1876; Janet, born around 1878; Frank, born around 1880; Claudine, born around 1882; and Bryant, born around 1885. They moved to Salem, Virginia, sometime after the Civil War, and her husband worked as a farmer there. He was living in Salem, Virginia, and working as a farmer. He died there on January 20, 1902, and she passed away of apoplexy in Salem on December 18, 1920.