I don't have any additional information on the Pirkles, but I believe I have some on the other side of your family. In family records of the Peters_Lewellen family, I show your mother, Margaret Louise Petree, daugher of Earnest M. Petree (1898 near Rosendale MO) and Susan Marie Stanton Petree (Jan 22, 1900 Fillmore, MO).
Earnest Matthew Petree was the son of James Henry Petree and and Cynthia C. Beall (1871 Resendale MO -1922 Fillmore MO) and James Henry Petree (Feb 19, 1863 near Rosendale MO - June 4, 1932 Fillmore, MO).
Cynthia Caroline Beall was the child of Reuben Pottinger Beall (Apr 12, 1845 Ohio) and Elizabeth A. Lewellen Beall (Jan 6, 1850 Preble Co, OH).
Elizabeth was the daughter of Nancy Peters (Feb 9, 1821 Franklin Co, VA) and Bafford Lewellen (June 7, 1820 Preble Co OH) They were married March 11, 1847 in Preble Co. OH, and are our common ancestor.

Bafford Lewellen was the son of Phillip Lewellen and Anna Runyen. I have found this branch of the family on the Ancestry site recently.

Nancy Peters was the daughter of John Peters and Elizabeth Gossett.

John Peters parents were Micheal Peters (June 23, 1748) and Magdalene Dillman (August 3, 1751).
Elizabeth's parents were Daniel Gosett (April 16, 1752) and Catherine Car (Feb. 14, 1756).

This research was done by primarily by Charles Anderson Lewellen and Clifford Peters Lewellen for the Peters-Lewellen family reunions that were held in the 1920's and '30s.

I sent a copy of this book (it was printed in a loose-leaf format so people could use it to keep up with the cousins) to the Mormon Llibrary in LA, which is where I started researching.

Hope this helps.

-Nancy