Corn, aka Maize, is a rather interesting and unique supporter of modern Darwinian Evolution.
Corn literally can not exist with out human kind, and specifically, humans with agriculture. The mutation that created the original spexies known as Maize requires deliberate intervention and preparation by another species (namely, humans) in order to continue to successfully reproduce.
Which means that Maize could not have come into existence until after humans had started farming.
either it evolved from other grains at a lucky place and time, quite possibly one of a multitude with corn being the only one we know about because it's the only one that was in the right place at the right time.
Or, it was placed via some direct but undocumented visitation from an intelligent designer at just the right point. in time, and there were never any similiar genetic variants that simply died off. Yeah, that's a magic man did it argument.