ÞINGVELLIR B1a on an interesting philatelic cover from 1953 that also has a clear impression of numeral cancel "172" on the front. Addressed to the United States.
KEFLAVÍK FLUGVÖLLUR B6e on a neat little registered cover sent from the Navy Exchange (a store for service people at the U.S. Navy base in Keflavík) through the Icelandic postal system.