Liz,
Thanks for the reminder - now that I look at your pictures again, they do seem more like clams than mussels.
In our chinese restaurants they are usually served with black bean sauce(they are great).

Pippies are definitely more clam-like in taste, none of the distinctive flavour of mussels. I use them when I occasionally make clam chowder. (For that purpose you can use the small clams with ribbed shells sold here under their Italian name, vongole, but they're more expensive and I don't notice any real difference in flavour.)

Stir-fried scallops with a little ginger, spring onion and rice wine are hard to beat too.