Name: Samuel Kingsbery
Location: Needham, MA
Date: 1756
Carver: HC Geyer

The earliest example of HC Geyer's distinctive skulls I've seen was dated 1769. As such, this carving is at least ten years newer than the date it bears. Probably from the 1770.
Not uncommon by any means. Sometimes families lacked the funds for a gravestone at the time of death.