Food is one of those ”strategic reserve” things, because you can’t just build farms and have them immediately start cranking out staple foods like a factory. The fed keeps strategic reserves of things that take time to create, but which have major short-term needs. A farm will take weeks or months to start producing, and farmers plan their crops literal years in advance.
And that “farms are only a few weeks away from producing” announcement is a cold comfort when people are hungry right now. Most of society is only about three days of missed meals away from violence.
The sad reality is that the south/central US produces a lot of food. Sure, there are other areas that food could be produced, but it’s not already doing so, meaning it would be useless in anything except the long-term. But in order to reach the long-term, you first need to deal with the short-term. And the short-term in this scenario has a lot of people going hungry.