Brad:
They are called the Meister Schaften or (Meisterschaften)dash badge (1955 ending date for 56, 1956 for 57, 1957 for 58). You can buy them at many 356 Vendors... Or, make it easy and go to JPS's site, look under parts, then call John Steele and get one quick and easy.
I could give you a "from the hip" guess as to their history, but my memory might be wrong. Someone here will give you the rundown on it's true meaning/representation.
Jim