Spencer Harrison was mentioned in the 19 April 1806 will of his father-in-law, Thomas Pitts, proved on 20 October 1806. [Essex County, Virginia, Will Book 16, pages 435–438.]

On 18 October 1806, slaves belonging to the estate of Thomas Pitts were divided between Spencer Harrison, in right of his wife Margaret Harrison, and Thomas Wright, in right of his wife Molly Wright. Received by the court and ordered recorded on 20 April 1818. [Essex County, Virginia, Will Book 18, pages 476–477.]