Greenbrier Hotel Pewter North American Wine & Food Festival 1976 Plate mark RWP. Greenbrier Hotel Pewter North American Wine & Food Festival 1976 Plate mark RWP. Greenbrier Hotel Pewter Wine & Food Festival 1976 Plate. This is a solid heavy pewter plate! Im not sure if Pewter can be polished so leaving in found condition. It is marked RWP twice on the back which is a pewter mark. Also marked Wilton Columbia PA on the back. The piece measures 10 7/8" and is a very thick heavy piece! Must see all pictures for your satisfaction. Free Shipping with USPS Standard Mail