Yes, white corn is considered a grain when it is harvested at full maturity and dryness.
When corn, regardless of its color (including white), reaches full maturity and is harvested dry, it fits the definition of a grain. In this state, it can be processed into various products, such as cornmeal, which is used to make tortillas, cornbread, and other food items. The maturity level at harvest is what determines if corn is considered a grain, not its color.
