It is a small CUD or die brake. It is a small CUD or die brake. A CUD is a die break connected to the rim. Pretty small and if a little larger would have some minor premiem say a couple of dollars.
You have a small cud and some peripheral die damage, possibly caused by banging against the entrance to the collar at a time when the die was misaligned. The cud was possibly knocked off at the same time.
