I can now confirm Mary PATTERSON as a daughter of Thomas PATTERSON and Sarah DENNETT.
My father remembered when one Karl GAMMON used to visit with my grandmother, they were cousins. So, with that little bit of information I started trying to fill in Karl's family tree. His parents were Edward B. GAMMON and Jessie E. WEAVER. Jessie's parents were William "George" WEAVER and Mary PATTERSON, making Karl and my grandmother 2nd cousins through their shared PATTERSON line.
So, with a little family story I was able to link them and I am now confident to add Mary PATTERSON to the list of Thomas and Sarah's children.