These are not from a brand or company. From 1936-37 up through the late 1940s these were grade certification plates, guaranteeing that the gas dispensed from the pump they were displayed on met the minimum standard for "Motor" "Regular" or "Premium". It was based on several criteria, but essentially was an octane guarantee by the state weights and measures board. There are matching decals, as well, and octane markings are still required for display on pump here in NC. They are not particularly rare here, but are getting harder to find.
Wayne Henderson
