Harriet Gaston was born around 1840 in Ohio to William and Sarah Gaston. Her father was a farmer who owned $5,000 of real estate and $1,000 of personal property by 1860. The family lived in Morefield, Ohio, until the 1850s, when they moved to Wingville, Wisconsin.
She married Orlando Thomas on November 9, 1865, and they had at least five children: Harry, born around 1868; Ezra, born around 1870; William, born around 1873; John, born around 1875; and Mabel, born around 1878. They lived in her father’s household in Wingville until the 1870s, when they established their own household in town. Her husband earned a living as a farmer. They moved to Gresham, Oregon, in the early 1900s. Her husband died on January 3, 1916. She applied for a widow’s pension later that month, and she eventually secured one. She died in Multnomah County, Oregon, on December 20, 1917.