The official heraldic shield of Workum

Workum’s shield is evident on the city seal as early as the 15th century. The oldest known city seal, dating from 1420, does not yet contain the current shield. Instead it contains a Gothic device, depicting St.Geertruid with a flower in the right hand and a palm branch in the left, and a kneeling monk on his left and his right. A second seal dating from 1496 (Van den Bergh) or 1426 (Nijefurd municipality) does show the shield with the eagle and the lilies. The shield reappears unchanged on all subsequent seals.

The origin of the shield in its current format is unknown. The ‘half eagle’ is a common figure on many individual shields in Friesland. It is therefore a distinct possibility that this effigy on the Workum shield originates with the personal shield of a leading citizen or mayor in the 15th century. The lilies may have a similar genesis, or may have its origin in the worship of the Virgin Mary, where it is also often used as a symbol of purity.

The city used the shield on its official letterhead.

The shield is divided in two lengthwise, with the right half featuring a black ‘half’ eagle on a gold background, while the left half is black with three golden lilies placed two together above the third. The shield is topped with a five pointed gold crown.

source: http://www.ngw.nl/w/workum.htm