Just picked this one up this morning, cannot figure out what type of error this is if any. Maybe a collar error or blowout?
I like the blowout description, Looking at the condition of your coin I say it's PMD - Post Mint Damage. Something crushed the collar's edge but not at the mint. It's from 1853.. I think that if that was a significant error someone would of noticed a long time ago. I submitted an old Jefferson nickel once to NGC that had the same blowout look. They returned it as a non-error.
Okay, nevermind...PMD....from this angle it looks like a brass brazing maybe for a jewelry mount or other purpose?
It looks like there is an indentation between the dentils and where the piece sticks out, is that correct? If so, it's post mint damage, someone squeezed it with something. I think it's improbably based on the indentation, and based on the fact that the striking pressure applied to the collar is just not that great. The striking pressure is greatest on the face of the rims as indicated by the frequency of cuds. These coins were struck in a collar. It's possible that a piece of the collar broke during the striking, creating something similar to a cud but sticking out of the coin. However, if that is what happened it would not cause the indentation. Further I have never seen this happen on any collar struck large cent, nor have I ever seen one reported. Not saying it's impossible, but it would be truly rare.
We had another one in another thread recently but I believe it was a Lincoln cent. I'm in agreement with a former mount of some type. A poor mans way of giving something nice to his beloved at the time period. And was probably quite attractive when new.
Large cents were popular as fobs for hotel keys and pocket watches for a long time--a possible use until it broke off.
