I photocopied your Emily's marriage when we were in Amherst.Just happened to be among other Gilbert marriage bonds (I believe).
Nov,22,1831 Emily Gilbert & Edwd. Davidson. SW: Humphrey Gilbert.I have no idea what SW means.
I noticed on the ancestry message board that one of your respondents referenced a letter connecting Mace to Humphrey and Pollina.That would be very good evidence for that era.I also found Humphrey on the 1810, 1820 and the 1830 censuses in Amherst Co.He didn't move on to Bedford Countyuntil after 1830.If Mace was Humphrey's son he must have been born in Amherst Co.
This is Humphrey's family to the best of my knowledge:
Henry C. GilbertMJudith Crenshawapprox.1778
Their children: William Ludlow1780-1862 Humphrey1782- Judith C.-1837 David Anderson1796-1866 There may be other children.there seem to be some large gaps.
We are counting on you to make the connection since it makes it for us too.Of course I still wont have a father for poor Richard.