Roster of Confederate Soldiers, 1861-1865, shows:

Poe, Larkin M. AL 28th Inf. Co.E

I do not show a Larkin M. Poe with any TN unit.

The Roster also shows:

Poe, Thomas G. AL 28th Inf. Co.E

28th AL Inf Reg organized for 3 years at Shelby Springs in March 1862 - field consolidation with 34th AL Inf Reg in early 1863 - consolidation with 24th & 34th AL Inf Regs & designated 24th Inf Reg Consolidated at Smithfield, NC 4/9/1865
Sifakis, Compendium of the Confederate Armies - AL , page 96