The Guardian has an absolutely heartrending and fascinating article about the scraps of material left with abandoned babies at London's Foundling Hospital:
In the mid-18th century thousands of poor women, similarly at the end of their tethers, deposited their newborn babies at the hospital. A sign instructed them to leave some kind of identifying token pinned to the child in the event they were one day in a position to take it home. Neither the name of the mother nor the baby would be recorded, so this token needed to be memorable and distinctive.
The hospital's thinking was not as punitive as it sounds. To give the child the best shot at a new life, the governors thought it best to erase its old identity. In that single liminal moment, one history would be wiped out and another begun – a new name, some basic schooling and, in time, apprenticeship to a useful trade. Just in case the mother's circumstances changed, though, she was advised to leave some piece of material evidence to prove the child was hers. The hospital promised that "great care will be taken for the preservation" of the item. In years to come the mother's description of that token would be her only way of proving she was the mother of the baby she had given up all those years ago.