Old lead backed button?

[Southern Brass]

I found this thing today that appears to be a button ( maybe ) that was once lead filled. The outer shell is brass with some shiny gold guild left on it. I used an old crusty wheat penny as a reference to size. The item in question is about the size of a 50 cent piece . The back has some lead left in it but most has rotten away over the years. There is no holes in it or no shank on the back. Any ideas what this could actually be and the age of it? Thanks for any help.

 

[Mud Hut]

That is a bridle rosette as well.

 

[Southern Brass]

Thanks... Is the rosette civil war era or later? Pretty sure its civilian and not military issue