Charlie This is what i have found so far there was a chancery case in Fluvanna courts file 1856and the case was heard in 1857
John H and George AMayo took Joesph Mayo to court to force the sale of the land grant that Judith Hunt Mayo widow of Benjamin Mayo received In May of 1856 only to die one week later in this case there is a summons for Joesph to appear in Fluvanna court sent to the Rockbridge county Sheriff. along with a letter from John H requesting the sale of the land warrant and the proceeds be divided among the heirs of Judith Mayo, which was John H.,George A and Joseph Mayo. also there is a response letter from Joseph filed with these court documents
Now in the 1820 pension application for Benjamin Mayo (son of James and Martha Williamson Mayo )he list 3 sons living at home ages 20,16 and 13 with there being documentation for John H being born in 1800 and George A being born in 1804 that leaves the third son Joesph being born around 1806 and 1807.
Now looking at the 1860 Rockbridgecensus you see Joseph having a birthday of 1807.
I am still working on getting more documentation before I say I am absolutely sure but right now everything is pointing in this direction i am in contact with 2 others who are working to figure this out alsobut i think this court case was the break we needed into solving this every couple of days we get new names of people who had contact with the family like who witnessed Joseph and Nancy's Wedding pernission