There is a gravestone for Martha (Singletary) Dunklee in the Meeting House Hill Cemetery in West Brattleboro, VT, which gives her death date as February 15, 1805.
I have just discovered that the date is wrong by three years!I found, on the New England Historic Genealogical Society website in the Early American newspaper collection, a death notice for her from the Federal Galaxy newspaper, printed in Brattleboro, dated Saturday, February 20, 1802.
This would certainly suggest that her gravestone was not placed at the time of her death, but at least several years later...and someone goofed!
Martha was the 2nd wife of Robert Dunklee, who moved to Brattleboro from Brimfield, MA in 1774.He died in 1776, and is buried next to Martha in Meeting House Hill Cemetery. Many of the earliest settlers in the area are buried here and there near the Dunklees.