We know that the Maya widely cultivated maize. This was one of their staple crops. This fact was common in Mesoamerica, as other groups, such as the Aztecs, also relied on maize heavily.
If this crop is not considered a trade item it most likely means that the Mayans did not trade maize with other peoples. This would suggest that all the maize that was cultivated by the Mayans was used for their own nourishment.