Well, if you pay attention . . it IS in the kids section, and that whole corner of the store is dressed up like a little barnyard. It is probably intended to represent "pretend" corn as a decoration for the kiddies, but their isn't a model for fake corn.
The level designers do this sort of thing a lot. Haven't you ever questioned all of the pallets of cobblestone in the garden center or in people's attics? Or the cement at the farm, lying in the cornfield? They are meant to represent things that SHOULD be there, but there are no models for.
I keep hoping that someday we will see more variety in those pallets.