Amazing, Peaks! You know, I considered the possibility that it might be a bag of some sort, but dismissed it because I could not think of a context in which that might be worn by someone deplaning in a suit and tie. Very astute. I'll recommend that you be appointed aviation consultant to AAAC.I be someone.
Squint. You'll see a second one on the other side of the neck. A dark bungee type cord holds them together. They're small sand bags, probably leather, used as ballast when riding in small planes of that era, if your actual weight was not enough to balance your side.