Which preposition to use with omer

in Occurrences 1%

C. III., son of the preceding, last of the Merovingian kings, from 743 to 752; was deposed by Pepin le Bref; died in the monastery of St. Omer in 755. CHILDERMAS, a festival to commemorate the massacre of the children by Herod.

of Occurrences 1%

In the worship of him a thousand truths are working, unknown and yet active, which, embodied in theory, and dissociated from the living mind that was in Christ, will as certainly breed worms as any omer of hoarded manna.

Which preposition to use with  omer