Mary was born to Capt Jonathan and Mary Southwell Sheldon in West Suffield, Connecticut.
In 1748 she married Rev. John Graham Jr. and together they raised seventeen children.
Mary's obit was published on May 27, 1776 in the Hartford Courat stating:
On Saturady, the 14th instant departed this life after eleven days of distressing illness, of the pleuricy, the virtuous and amiable consort of the Rev John Graham of Suffield, 51st year fo her age with whom she lived twenty eight years to a day. She left him with ten children to mourn the loss. She was truly an excellent and virtious wife, a loving and faithful mother, a generous and bountiful benefactor, a real and hearty friend, a kind neighbor,a modest, meek and exemplry Christian. Her remains were decently interred on the 16th inst. When a sermon suitable to the occasion was delivered by the Rev Mr Gay, from Psalms 38 and 18: Lover and friend thou put far from me, and mine aquaintance into darkness.