look at united and, the wreath above the d in dollar. It must be zoomed in to see, but there is a 3 on the left side of the wreath tie Tell me something good.
Looks to have been counter stamped after it left the Mint. In this case it is damage. Just a 3 alone really has no significance. Some counter stamps can be valuable if they can be traced back to something important. Like a store owner, a G.I. dog tag number, or initials, etc. Early pilots in the Air Force would carry a counter stamped silver dollar in case their dog tags were lost and this way they might still be identified if KIA. The other marks might possibly be a die clash.
Agree with Jim. Look at it on the side it is clearly an M. Not only does it not add value, it loses value from this damage.
I was looking at it from the wrong angle and was mistaken about the M. Was looking from your vantage point as it being a 3. I take that back as the others are correct. Apologies.