This post is one part biography and one part mystery. Although I know some about Mattie from interviews with family, I have been unable to trace her family past her. I've stuck with this one pretty tenaciously because there is a family story that we "are related to either Lewis or Clark of the Lewis and Clark expedition" via my great grandmother, Mattie. I'm hoping that by posting this information, someone who has some of my missing pieces will see it.
I started at both ends... by researching Mattie and also by researching William Clark and Meriweather Lewis. What I was hoping is that by staring at both ends, I could try to narrow down the possible relation connections and/or find a link to Mattie via the known descendants of either man. That didn't work out as well as I'd hoped.
My great grandmother, Mattie Clark, was born 2 Jun 1878 to Jam Clark and M Parmellia Lewis Clark in Tennessee.  She does not have an official birth record or a delayed birth record with the state of Tennessee. As of the time of her death, she had the following half brothers and sisters : Ed Clark, Nashville, Mrs Myrtle Bateman and Mrs EJ Wyatt, Erin, TN and Mrs L O Rye, Birmingham, AL. John Clark, Tennessee Ridge, TN . Being that the males have the last name Clark, these half siblings are likely her father's children with a different mother and are most likely born after the 1880 census in which James appears with Mattie's mother.