Hi Debbie, In case you didn't have easy access, I looked in the Knox Co. Cemetery books, which are very thorough, and the Knox Co. death record book (1867-1908). No info on Samuel & Sarah/Sally Morrison.There is a Sally Morrison listed, but that one is born 1844 and had a maiden name of Gordon.Perhaps the stone was unreadable when the books were compiled.
I've been searching for the parents of Mary Polly Biggs (b. 1816) who married Joseph K. Butler in 1833.One of their older sons was named William, a name which does not appear in this Butler line in earlier generations.So I suspect that William Biggs is her father.The father of Joseph K. Butler is Benjamin Butler, who helped found Mount Vernon in Knox Co.In the 1820 Knox Co. census, the family of William Biggs had a daughter in the correct age range.
I wonder if she is a daughter of your William & Rachel Harrod Biggs?