WW2 GERMAN NAZI RARE Traditions-Mützenabzeichen [tradition cap badge] for the RAD's Arbeitsgau I Ostpreußen [East Prussia] SWASTIKA PIN RELIC FOUND Teutonic Shield badge
The white shield with the black cross was the coat-of-arms of the Deutschritterorden (Order of the Teutonic Knights, see Teutonic Knights - Wikipedia, the free encyclopedia ) who were heavily active in the east.
Thus, in their memory and as a sign of the continuance of their traditions, it was adopted as a symbol by the Arbeitsgau Ostpreußen [Arbeitsgau East Prussia] as well as the Bund Deutscher Osten [Union of the German East].