I know many of you will be excited to learn how to tell the difference between a chestnut and a buckeye, right? It's easy if the hull is still on the nut: a chestnut hull is composed of lethal spikes and cannot be picked up; a buckeye hull is smooth and softish.
But if the nut itself is sitting on the ground out of its hull, you can tell a buckeye by its perfectly smooth and unarticulated surface (other than its oval umbilical spot). A chestnut has a little pointed tip opposite its more squared-off umbilical spot. A chestnut also is more of a, well, chestnut brown, whereas a buckeye is a very dark nearly black brown.