Mike, The Howell Adam Rayburn buried in Flint Creek Cemetery isn’t Doc Rayburn. Howell Adam Rayburn was a resident of Pontotoc County, Mississippi, in 1860. Doc (also known as Rayburn the Raider and Yellow Doc the Ranger) was a Texan, and he enlisted with his brother, Milton V., in Company C, 12 TX CAV (Col. William H. Parsons) on 21 Oct 1861. When the regiment was in Des Arc, Arkansas, Doc became ill, and remained behind when the unit moved on. He eventually formed a partisan company of Arkansans and spent the war raiding Union Troops in an area between Searcy and Devall’s Bluff. His death is a mystery. Some say he died in Des Arc, Arkansas, at age 27 (the 1850 Census for Shelby County, Texas, shows his age as 9, which makes his birth 1841 and his death year 1868). According to an undated article reprinted in the Marshall (Texas) News (taken from the Fort Smith Times Journal), Doc found his end in an unmarked grave. Historian R.D. Keeble of Cabot, Arkansas, gives his place of burial as Old Oak Grove Cemetery, Des Arc. Doc was quite a colorful character, being a duelist, as well as an imaginative horse thief, the talents of which gained him his famous steed, Limber Jim. It is possible that the Harvell Rayburn mentioned in the letter was actually Howell. The Archer County, Texas, attorney might have been confused by second hand information thinking that Harvell and Howell were two different people. I have not found any census record of a Harvell Rayburn

There is a picture of Doc in uniform at:

http://www.rootsweb.ancestry.com/~arprairi/DocRay.htm