First... the letters are actually PC (or CP), not PG. So it cannot be a Pelican Guards button.
I said PC or CP because the photo is too out-of-focus for me to be able to determine their intended reading order. Generally, on buttons where the initials for a two-word organization are superimposed, the organization's first initial is "on top of" the second initial -- especially on the left side of the letter.
There is general agreement that none of the buttons Alphaeus Albert attributes to the Pelican Guards, with the possible exception of LA-23, are actually connected with that military unit. The lettering style on LA-24, sometimes refered to as "Lobate-serifs" lettering, same as on your button, became popular in the post-civil-war era, and is found on
many-many postwar era buttons. Notice that the most common version of GAR buttons -- all of which are postwar -- has that lettering-style.
Your button's back has a very peculiar look, almost seeming to be a 1-piece rather than 2-piece button. (Perhaps it's just due to being out-of-focus.) That look, along with the backmark which begins with "NAPOL" makes me think it may be foreign-made, possibly Italian. No offense inteded, buy, if possible, please make some well-focused closeup photos and post them. Does your camera have a Macro-focus button? (It is usually indicated by a flower icon.)
Edit: Literally laughing-out-loud. Once again, Nhbenz and I were typing at the same time --
and we said almost exactly the same thing... even including the "PC or CP."
