That's caused by a die chip. The low points on a coin correspond to high points on the die used to strike it. On the die, the center of the 4 is a small high point. Under the stresses of striking, sometimes those high points break off of the die resulting in what you see on your dime.
For some people, they make interesting conversation pieces especially if you collect different types.........like filled numbers 6, 8 or 9 and filled letters like A, B, D, etc. Chris
Whelp... "worth" would depend on why you're collecting, right? If you're only in this with the hopes of an easy future windfall, then no... its certainly not worth it. However, if your collection consists solely (or mostly) of coins you enjoy, and you think you would feel the same about this one, then of course it's "worth" adding. Your collection is YOUR collection, so add to it whatever you like and not what someone else does or thinks you should collect.
Sure, if you can afford to spare the dime. As mentioned not monetarily valuable, but a nice example of a die chip (there is another one filling in the P) and also a nice example of a late die state showing heavy die flow lines in the field and on the bust.
