The Barnum Family, 1517-1904 lists his given name as Wills, while The Barnum Family, 1350-1907 calls him Willis Barnum. The Commemorative Biographical Record of New Haven, Connecticut states that "Mills was a farmer in Litchfield, and died in East Hartland, whither he had retired to pass the rest of his life."
In the 1850 US Census for Litchfield, Litchfield County, Connecticut the family of Mills Barnum was enumerated as follows:
Dwelling #145; Family #159
Mills Barnum, 43, M, Farmer, b. Connecticut
Caroline Barnum, 44, F, Real property $2,800, b. Connecticut
Philetus Barnum, 15, M, b. Connecticut, Attended school within the year
Lucyann T. Barnum, 9, F, b. Connecticut, Attended school within the year
Calvin Barnum, 41, M, Farmer, b. Connecticut [Note: Calvin was a younger brother of Mills Barnum].