Mary was a teenager when her family emigrated to Canada. In Canada (and later in the United States), the Harris family were victims of discrimination due to their immigrant status as well as their Catholic faith and Irish heritage. Mary received an education in Toronto at the Toronto Normal School, which was tuition-free and even paid a stipend to each student of one dollar per week for every semester completed. Mary did not graduate from the Toronto Normal School, but she was able to undergo enough training to occupy a teaching position at a convent in Monroe, Michigan, on 31 August 1859 at the age of 23. She was paid eight dollars per month, but the school was described as a "depressing place". After tiring of her assumed profession, she moved first to Chicago and then to Memphis, where in 1861 she married George E. Jones, a member and organizer of the National Union of Iron Moulders, which later became the International Molders and Foundry Workers Union of North America, which represented workers who specialized in building and repairing steam engines, mills, and other manufactured goods. Considering that Mary's husband was providing enough income to support the household, she altered her labor to housekeeping.