For those of you who do not know, there are two kinds of basic corn: sweet corn and field corn. Both are consumed by humans. The first usually eaten as ears or cut into kernels and frozen or canned. The latter is dried and the ground to make cornmeal or masa flour. Masa is the main ingredient in tortillas or in the "bread" of tamales.
The way that many First People ate corn was by dehydrating it to save it for the rest of the year, and then parching it. Here's some information on how to prepare that.
[link to www.utahpreppers.com
[link to stealthsurvival.blogspot.com
[link to www.preparingtosurvive.com
As you see, Western Europeans explored the New World, and adopted parched corn for their supplies. It packs a huge amount of nutrition in a pound of grain, far exceeding wheat.
Doing this for a long period, it will wear on the enamel of your teeth and wear them down. We don't think about such things now, as our food is mostly tender, but the longer a food is cooked, and the ways in which it's cooked, alter the nutritional value gained.
So of course, they ground it with crude mortar and pestle devices. There's a little information about that in the 3rd link.
Most people like it. In a collapse, there is little doubt that eating field corn will become commonplace.