Green’s Dictionary of Slang

acknowledge the corn v.

also acknowledge the malt, own the corn
[? in a horse-stealing case in a western state, the defendant, accused of stealing four horses and four feeds of corn, declared I acknowledge the corn but denied the actual horse-stealing. ‘Legend says he was lynched in spite of the admission’ (Ware)]

[mid-19C–1950s] (orig. US) to admit an error.