Is it the same size as an HJ armband diamond? If so, it's probably the unused center of a NS Stundentenbund armband. Looks just like the flag Pat posted a picture of.
YOU ARE ALL RIGHT it is the centre for the HJ studend armband. It would appear some US vets aquired a hoarde of these in the factory and have just recently sold their war booty reflected in the fact there are many of these around right now