Small copper coin

Hi
2.4 gram, 19 mm
one side totally unreadable

It was a button, I think.
Something a little like the one in this topic ...
https://en.numista.com/forum/topic59421.html
as 1) yours similarly has a crown at the top and a circle below,
then 2) inside that a small circular area where the loop was,
and 3) as other side is blank.