United Mine Workers of America.
The American Mining Union U.M.W.A. was founded in Ohio in 1892. Various U.M.W.A. badges were sent over to the UK in 1984 and distributed amongst the pickets and union representatives. Mr Arthur Scargill had one of these sew-on patches (as seen in the featured image above) on his baseball cap while he was at the Orgreave Coke Works in June 1984.
The badge (as seen left) is a small enamel pin-back badge issued in 1984.