Mussels were not commonly considered food in the US until after the war. It's a shame they were overlooked for so long. The Indians ate them, as do crabs and diving ducks.
Mussels have a remarkable capacity for holding on to things. Photo shows mussel farming, on ropes, in deep New Hampshire waters.
Our Atlantic Blue Mussel is the edible variety - not the deeply-striated Horse Mussel. I can eat pounds of them, steamed in white wine and shallots, but Mussel Soup is good too. In my experience, kids love mussels.
Try cookin' up some mussels this weekend, with some good bread fried in olive oil to sponge up the juices.