Two common styles of confederate button worn by the AOT were the puff block I and the solid cast block I. Many of these have been recovered in Tenn and Ga. I have a picture of both on the following page.
http://www.angelfire.com/ma4/j_mayo/csequip.html
Many of those troops would be wearing a Columbus Depot jacket.
http://www.geocities.com/Pentagon/Quarters/1864/cdjacket.htm