Customs Seal, Prussian, Image & Found by FLaSH.
Found in Surrey, 33mm.
Eagle displayed, inscription around // crowned FR ligature, BUREAU DE LANDSHUTT around
From Folkert, "Its indeed a prussian seal of Frederick II, The Great (1740-1786). One side shows his monogram FR Fridericus Rex (King Frederic), the other side shows the Prussian eagle holding sword and sceptre. The legend on this side should read REGIE DES DROITS DU ROI. The seal you have found is a Prussian customs seal, the name Landeshutt should refer to a city in Prussia, not to Landshut in Bavaria."
From information supplied my Michel Royer, see Kamienna Góra, (Landeshut in Schlesien).