My weed pulling this past summer took a 2 month hiatus. This resulted in a plethora of mature weeds. Had these adult volunteers along the driveway.
After searching the web for weeds that look like corn, I am fairly confident that it is Sorghum bicolor (millet or milo). Very attractive food crop (not weed).
Milo seeds are commonly found in most birdseed mixes. And yes, I was feeding birds in that area! My normal method of feeding birds is to grow plants that provide food, but sometimes I just set a bowl of seed out on the driveway:)