Not sure about this "E" stamped copper. Button????

[Smilodon]

Went to a site I have not been to in over a year. Pulled this out along with items from the late 1800s. My friend found one a long time ago and it could not be identified. It had a section on the outer ring that looked as though it was clipped away. However it did not have a hole in it like this one. Any ideas

 

[fyrffytr1]

There has been much discussion on this site about these "buttons" but i don't think they have ever been positively IDed.

 

[trikikiwi]

My thought is E for Earth. Is it an indicator on an electric plug or switch, or similar?

 

[taz42o]

Yes there have been many posted here but no ID.
I have wondered if they are from an Edison product.

 

[gman7665]

Maybe its an 'M' ? the hole is above an 'M' so maybe someone used it as a pendant or just a string or wire ? Maybe just a Tag Just My thoughts