I happened to come across this item which dovetails in this thread:

PAROLE OF HONOR
Provost Marshal’s Office
Opelousas, La, April 28, 1863
I, Captain Benjamin F. White, Opelousas, hereby give my parole of honor that I will not take up arms, or in other manner act against, or to the prejudice of the United States, until duly exchanged as a prisoner of war.
Signed: Benjamin F. White
Witness: (Unreadable – really fancy handwritten signature)

(White was a company commander for CSA Col Joseph Porter in NE Missouri.)