Not a Seal, Lead Horn Book, Image & Found by zx10rMark.
Found in Market Weighton East Yorkshire.
A small sheet of lead with five rows of characters on each side. One side has patterned row above the alphabet (with a retrograde S) and the other possibly a name - (T)HOMAS / BROTHER (again with retrograde S) / (I)DDEBOM / ESME FEK / IT. (a grid) IO>e
Horn books were originally a single page protected by a transparent sheet of horn, primarily used in teaching children to read. It was easier to make them from lead like this one.
See HISTORY OF THE HORN-BOOK from the Spectator Archive.