Oh yes; you can slaughter millions of extra cows and pigs in the US to realize a huge number of available calories, while redirecting the grain back to humans, all with no more ethical worries than you've already accepted in producing & consuming meat. A number of other inefficiencies can also go away under emergency conditions -- people will get less picky about their fruits and vegetables in a hurry, and it won't spend as long on supermarket shelves anyway.
From purely a US standpoint, yeah, I suspect our agricultural buffers are good enough for anything but a "volcano blotting out the sun" level deviation from the norm. Call it, four sigmas of food security. You'd need an event that only happens once every ten thousand years or so to really bring the US to its knees, agriculturally.
My point is -- I don't think food prices will shift much as long as the buffer is positive. If our margin narrows -- less livestock, more of it grass fed on marginal lands, grain spending less time in silos before being processed into food -- to two or three sigmas of food security, I don't think that you'll see food prices rise significantly, from market pressure.
I think if things go badly (and there's no guarantee of it at this point), it happens slowly at first, and then quickly, and you can't just point at food prices being low to say it's not about to turn from slow to quick.