Copper Queen Stores were located in Douglas, Naco and Bisbee Arizona. I can't find a company history, but find that they were in business from shortly before 1900 until the 1930's.
I would guess it to be from work clothes, but maybe seeing the back would give clues as to its use (specifically, was it a rivet-type button?).
Agreed on that dog license -- coolest one I've ever seen, and early too!