A typical example. Anecdotally, a young man would give a love token to his intended who would continue to carry it around, or throw it away if she failed to return his affections.
The majority are clearly made from William III sixpences. I've seen a few examples that are later, and a few made from lower value coins. The coins usually appear to have been rubbed flat before being bent twice into a very distinctive S-shape. These are found in greater numbers than the unmutilated coins, supporting the idea that they were deliberately disposed of.