Need an Army button expert.

This is from the area where I've been digging for a year now. The entire city burned down in 1893 but it could be newer for all I know. I only assume it's old since the metal is rotted and has a white mineralization.

 

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I took one of what @i need help found, on the right, reoriented it and paired it with OP's......looks pretty darn CLOSE, as she said!!!

 

Sweet, it hardly made a sound on my metal detector, but today I decided to dig every signal no matter how deep. Found an old keyhole from a tiny chest and an axe head as well. Soon I'll get out there with a dozer to shave off another layer. Thanks for the help everyone. Couple that with a person's house nearly burning down because they don't know how to "burn pile"; this was an interesting day.