Odd Brass Disc

[cambria09]

Hello All. I found this brass thing kinda deep near an old store built in the 1920's.

It has no markings, is 1-3/4 inches across, and center hole on the back is threaded. Let me know if you have any ideas.

 

[Beeps in my sleep]

Could that be part of a pocket watch backing?

 

[kingskid1611]

If brass it could be a part of a bell

 

[Back-of-the-boat]

Part of buzzer, the button.