Mary was born in 1799 to a poor family in Lyme Regis, her father was a cabinet maker and she was one of 10 children (although only her and her elder brother, Joseph, survived into adulthood). She was fortunate to be able to learn to read and write at the Sunday School of the Congregationalist Church her dissenting parents attended. Yet as a girl from a poor working family in the early nineteenth century her opportunities were limited, probably working from home before marriage and motherhood, and a likely hand to mouth existence.