What is the name of the black pin that one wears at a funeral, and are there any customs around them to know about? It's a black circle, pinned, and there's a black ribbon affixed to it.
There is a Jewish practice to tear one's clothes when in mourning. In recent times, it has become common for non-Orthodox Jews to tear a black ribbon pinned to their clothes rather than the clothes themselves in order to avoid damaging an article of clothing.
I am not sure whether using the ribbon satisfactorily fulfills the obligation according to the letter of Jewish law, but at least Chabad.org seems to imply very strongly that it does not.
How shallow, how disappointing, how pitiably trivial, therefore, to symbolize these authentic sentiments not by an act of historic and religious significance, but by the little black ribbon or button--invented by enterprising American undertakers!
As far as a name goes, I don't think there is any special name for this. I think it is generally just called a black ribbon. I have heard some people refer to it as a "keriah ribbon" after the custom of keriah (tearing).