Sharon, My best information is that Robert C. Pannell is the son of Wiley Ephraim Pannell and Ellen Elizabeth Dye. Wiley's parents were Richard Walter "Dicky" Pannell and Elizabeth "Betty" Grubbs; Ellen's were Jonathan and Dorcas Dye.
Dicky was son of Anderson Pannell of SC, his father was William Pannell, Sr.Betty's father was Enoch Grubbs, Jr. whose father was Enoch Sr.Betty and Dicky were married in SC and moved to Pontotoc Co. about 1848.They had at least 13 children.
Lot's of luck on your research. We old folks need you to take up the work.