I can read "EXTRA" from the photo, and I think if you clean it a little more, you will be able to see the read of the script. Warm perixode and Q-Tips work wonders. Breezie
It a civilian button called golden age button. It dates 1820'to'30's I can see several of the letters and EXTRA on the back. Soak it in a 50/50 mix of lemon juice and water for a bit take it out every now and then and lightly bursh it with a toothbrush. Keep an eye on it and don't leave it in to long. It looks like it has a good amount of gold gilt left and should clean up pretty nice.