Green’s Dictionary of Slang

1. a Confederate soldier.

1864		C.A. Fosdick Frank on a Gun-Boat 118: Come, you corn-fed, march [HDAS].
1867		G.E. Clark Seven Years of a Sailor’s Life 238: Jest as true as I am a corn-fed, and that’s a fact.

2. money issued by the Confederacy.

1865		J.R. Dennett South As It Is (1965) 232: This ‘corn-fed,’ as we used to call it, I never had no confidence in it.
1883		(ref. to 1861–5) Gerrish & Hutchinson Blue and Gray 303: The Union troops were often supplied with a bogus issue of ‘corn-fed,’ which they very liberally circulated whenever an opportunity allowed [HDAS].