what kind of button is this?

[jerseyben]

Dug this button on an old farm. I dont know anything about buttons. Any idea what this button is? It appears to have some sort of iron on the reverse (rust). It is pretty thick and about the size of a nickel.

 

[Breezie]

How about making a pic of the back of the button. Breezie

 

[jerseyben]

Here are some better pics: