Anglosaxons OFFA penny, very rare

Description

ANGLO-SAXON,  OFFA coin, beautifull condition, 1.45 grams of silver
ANGLO-SAXON, Kings of Mercia. Offa. 757-796. AR Penny. London mint; Ealhmund, moneyer. Struck circa 779-792/3. O F A (RX) within the angles of a lozenge cross fleury with central pellet-in-annulet surrounded by four pellets / +/ALH/MUN/∂ divided by a beaded bar with fleury ends. Chick Type 39 (variety unlisted); SCBI –; BMC –; North 282; SCBC 904; EMC 2011.0257 . Near EF, toned, some deposits. Very rare.
Found near Bedfords Farm Beef, Essex, 1750.