It has been quite some time since your comments were posted but I thought I would give this a shot.
My Mathis is Nancy Caroline Mathis who was married to Thomas Johnson Erwin. My records show her parents as James and Nancy (Jones) Mathis but i am not sure of this. Their oldest daughter was Elizabeth Rebecca Erwin who married Joseph C. Epley. Therefore I am sure the Mathis family that you refer to is my line.
If you are interested in corresponding I would certainly like to find out more information on this family and would be happy to share what I have.