The pattern of this scarce Mason's pearlware plate is known by 3 names: "Fountain", "Hercules Fountain", and "Trentham Hall, Staffordshire". The pattern can be seen in the amazing database of the Transferware Collectors Club. A description of it can be found on page 369 of "The Dictionary of Blue & White Printed Wares, Vol. 1" by Coysh & Henrywood.
I was surprised by the simple mark on the back of the plate: "SEMI-CHINA WARRANTED". But both of the sources above show that to be the correct mark for this plate by C.J. Mason & Co., c. 1829-45.
The 10" (25.5 cm) plate is in very good condition. There are no chips, no cracks, and no repairs. There is crazing which is most visible on the back on the plate. There is also discoloration only on the back of the plate.