It always amazes me how much military accouterments are found in the ground...that's a nice hat pin and does appear to be vintage. A google search to identify it only confused me....the emblems all seem to look alike except for the color and the top/round portion's design and stars. The different designs seem to identify with WWII, Korean conflict, WAC, etc. The Air Force was still using a version of this emblem on wheel caps when I retired three years ago, but I don't know about other branches. In the Air Force, an emblem like yours would belong to an officer--if the emblem had a circle around it, it would belong to an enlisted person. Congrats on saving that history!
