I've not been inattentive, just busy. David Rosenbaum mentioned 'a turn of corn'. Generally speaking, a turn of corn was the amount of grain in a sack that could be easily carried by hand or across a horse when going to mill. The amount would produce enough meal for a few days, thus many went to mill once a week.

Interestingly, 'wait your turn' is a phrase thought to have begun with men or boys waiting for their meal in the order in which they arrived. Also, a meal or time to eat, comes from the bread produced with ground grains served at each and every sitting. The use goes back at least to Old English. And corn as we know it in America was not known in Europe. Corn there was simply grain. --Mike