Cockles are small, edible bivalves. Traditionally sold with winkles and whelks, cockles have been a popular British seaside snack for many years. They were also sold outside London pubs by vendors who, in the absence of scales, used a pint glass as a measure. They've been sold by the pint ever since.
Live cockles in their shells are available from some fishmongers. Cooked and shelled cockles can be bought in jars, preserved in brine or vinegar.
Cockles can be used in seafood pies or tossed into salads. They can be eaten raw or steamed until their shells open, like mussels. Use them in soups, risotto and paella or stew them in a tomato sauce and serve with pasta.