The following data is extracted from Genealogy and Biography of Ontario County, New York.
William, son of Joseph Blossom, the first member of this family of whom we have definite information, was born in Amsterdam, New York, and was probably a descendant of the Cape Cod, Massachusetts, family. A number of Blossoms are mentioned in the records of Barnstable and Sandwich, and the name is associated with Wells, Vermont, through a descendant of the Cape Cod Blossoms. William, son of Joseph Blossom, was in Manchester, New York, before 1837. He had been educated for the Presbyterian ministry, but did not enter it. He engaged in farming in the town of Seneca township, and in 1847 he came to Port Gibson, where for a time he ran a general store and engaged in the wholesale egg and butter business. He married (first) Magdalen Post, and (second) Polly, daughter of Eli Benham. Children, all by second marriage: Joseph, referred to below; Delanie; Magdalen; Eli; Henry; Samuel.
Source: Genealogy and Biography of Ontario County, New York