Hello Bryce,
You might wish to try the Joseph Graham Papers published in the 1930's. I know the U.S. Army Military History Institue in Carlisle, PA has a copy (in their superb new facility still run by the superlative Dick Somers) and also Duke University or UNC at Chapel Hill. Graham was a member of the 27th North Carolina Infantry Regiment of Cooke's Brigade & rather prolific at writing letters.
By the way, how is the Petersburg Project coming along?
Good luck,
John Pearson