Lawrence K DuBois

I have been looking for the parents of Lawrence K DuBois, (my 2 times Great grandfather), for many years. He was born in Tompkins County New York according to family history, FAG and other sources in 1820. Judging by documents for land patents he signed with an X indicates he was illiterate. There are a couple theories as to who his parents were but no concrete evidence has yet been presented. I have found only two DuBois families in Tompkins County census records that fit the time frame of his birth. Henry (Hendricus) DuBois & Nelly Covenhoven, and Garret DuBois who resided in Caroline in 1830. Any and all help appreciated! Thanks, John M Novak