Stadtwappen Hamm Coat of Arms......City of Hamm, Germany.
http://www.houseofnames.com/hamm-family-crest is a great place to research The Surname Ham/Hamm Crest and History.
It provides all of the very oldest and origins referencing the old world clans, notables, migration, and territorries.
"Gunn - Clan is associated with Hamm's" see the information here.