Note on the 'R' that is a die chip. but on the 'B', that is a broken post on that bottom of the 'B'. When the post breaks off of the die, the void left on the die coins will show a filled with area like on your coin. These can break off the die in segments or all at once. These can be seen on closed devices. (Not the same as a die chip, as the chip is a broken area on the die. The broken posts are seen on closed devices. Sometimes called filled devices, but the same cause of a broken post.
And even below the surface of the post, making the mintmark/devices over filled on the devices.
These are not collectables, but just information that will help you understand them when you see the while searching coins.
CoopHome: What is a broken post and how is it different than a die chip? chips can happen on any area of the die, but a broken post is found on closed devices.