Are they still green or dry?
Your biggest problem is going to be mold. The trick will be to get them dry ASAP, and keep them that way. The best way to do that would be to leave them standing in the field and not water them...since that's not an option, chop them at the base (do not pull, tilling in the roots can be beneficial to the plot since corn roots add various things into the soil, you wouldn't want to remove them.) and stand them up as individually as possible in a nice sunny spot that gets no water. Best way to chop them is with a nice sharpe scythe or (barring that, or knowledge how to use one as they can be quite dangerous in the unskilled hand) a sharpened hoe.
Dried, they can last quite a while. But, mold, well, you don't want to keep that around. Once dried bundle them up and handle as little as possible as they will be brittle.
To be honest, some of mine from last year have yet to rot, and could be stood up right now, but would look VERY disgusting...which might not be a bad thing all together...
Minor comment to be careful if you have allergies. Dried corn is one of the few things that make me have to grab for the inhaler.