2 matching 9-1/4" pewter plates stamped Grenfell - London. Grenfell lived from 1734-1784.
One plate has clearer markings of a Winged Griffin on the left side of the back with a rope chain design underneath and under that is the name "Grenfell" On the right side of the back side is the stamped "Made In", then a Crown below that, and then under that is the word "London" Upside down under those 2 marks is the stamped "Super Fine Hard Metal" inside a scroll border.
The other plate has the same markings but not as clear. The previous owner of the plates cleaned the areas around the hallmarks.
On the front flat rim of each plate are the initials "E + G" (last photo).