2013-D Mount Rushmore Quarter

It's not a Cud, but a die chip. These are quite common and not of much value, if any. A small hole was made when the tiny section of the die near the worker's cuff and boot chipped and fell away. Die chips can occur anywhere on a die. This differs from a Cud in that a Cud involves the edge of the die breaking off, which leaves an area on the rim of the coin with no detail from the strike.

This image shows a Cud and the resulting weak area on the opposite side.

Or even just damage from a hit. On the coin is there metal movement between the rim direction and the boot. If so, then it could be coin damage. A chip is not a premium for the coin. It is just a die event. Not to be compared a Cud. A Cud is an end of the life of that die, when it is pulled and retired. They are mostly defaced and sold, or defaced and recycled.