I collect WWII US militaria and this was supposed to be WWII USMC IV Air Wing patch. The Roman Numeral I is offset so the V could be next to the I for the IV Marine Air Wing. First Air Wing patches have the I centered. The patch is unfinished, which is not uncommon at all for WWII. Some were unfinished or have mistakes in them. Even though the patch is unfinished, many people collected patches during WWII, and often didnt know if there were mistakes in the patches (or didnt mind). Some people would try to collect as many different units as they could and sewn them on blankets (often green army blankets, which might explain the green thread). Once in a while you may see one of these WWII "patch blankets: for sale on ebay. Anyway, the patch has the correct WWII cut edge style (post war patches usually had a merrowed edge which prevented the edge from unraveling). Also, if you put this patch under a black light, it should not glow (post war patches or repros will usually glow from synthetic fibers). Unfinished/mistake patches usually are worth considerably less than the finished ones.