She was the daughter of Captain Jonathan Wolcott (1639–1699), and his wife Mary Sibley (1644–1683), both of Salem, and was about seventeen years old when the allegations started in 1692. Her aunt, Mary Woodrow, the wife of Samuel Sibley (1657–1708), was the person who first showed Tituba and her husband John Indian how to bake a witch cake to feed to a dog in order that she and her friends might ascertain exactly who it was that was afflicting them. Joseph B. Felt quotes in the The Annals of Salem (1849 edition) vol. 2, p. 476 [from the town records]:
March 11, 1692 – "Mary, the wife of Samuel Sibley, having been suspended from communion with the church there, for the advices she gave John [husband of Tituba] to make the above experiment, is restored on confession that her purpose was innocent."
At the trials, she was said to be calm, but subsequently critics have accused her of everything from compromise to actually being a witch who foiled her potential adversaries by distracting their attention away from herself onto innocent persons. She married Isaac Farrar on April 28, 1696. Isaac was the son of John Farrar of Woburn, Massachusetts. They had several children, and eventually moved to Townsend, Massachusetts. Mary Wolcott also married David Harwood in 1701 in Sutton, Massachusetts. They had nine children:
- Mary Harwood, b. Abt. 1702.
- Emma Harwood, b. Abt. 1705. (m. Ebenezer Macintyre, 23 May 1728).
- Hannah Harwood, b. Abt. 1706; (m. Ebenezer Twiss).
- David Harwood, b. Abt. 1708, Salem, Essex County, Massachusetts; d. 22. August 1781, Sutton, Worcester County, Massachusetts; (m. Margaret Cox, 13. March 1730/31, Salem, Essex Cnty, Massachusetts).
- Elizabeth Harwood, b. Abt. 1711; d. Abt. 1738; (m. Benjamin Moulton, October 1734).
- Ezra Harwood, b. Abt. 1715.
- County, Massachusetts(m. Jonathan Nourse Jr., 12 August 1743).
- Absalom Harwood, b. Abt. 1723; (m. Anna Boyce, 23 September 1748).
- Solomon Harwood, b. Abt. 1725; (m. Abagail Phelps, 20 December 1748).
They removed to Sutton, about 1729, leaving most of their children living in Salem. David was a weaver by occupation. David died before 1744; his wife Mary probably died before 1752. 
- Sidney Perley, The History of Salem Massachusetts (1924–1928, 3 volumes)
- Essex Institute, Vital Records of Salem Massachusetts (1918–1927, 6 volumes)
- Melindi Lutz Sanborn, Essex County Massachusetts Probate Records, 1630–1840 (1987, 2 volumes)
- Ithamar B. Sawtelle, editor, History of the Town of Townsend, Middlesex County, Massachusetts ... 1676–1878 (1878)
- Henry C. Hallowell, Vital Records of Townsend, Massachusetts (1992)
- Ezra S. Stearns, editor, Genealogical and Family History of the State of New Hampshire (1908, vol. II) p. 591 [Family of Isaac Farrar]
- U.S. and International Marriage Records, 1560-1900 Record Name: Mary Wolcott Gender: female Birth Place: MA Birth Year: 1675 Spouse Name: David Harwood Marriage Year: 1701 Number Pages: 1
- University of Virginia: Salem Witch Trials (includes former "Massachusetts Historical Society" link)