Yesterday I visited the Foundling Museum, which is on the site of the old Foundling Hospital.
This a poignant photo of some of the mementoes that impoverished mothers left behind when leaving their babies there - these were used as ID if ever she were able to come back in the future and reclaim her child. The children were given a number and their names changed.
If you click and enlarge the photo you'll see that they're things like buttons, coins with a name scratched on, or an inch of cloth from a dress. 
A very interesting museum and well worth a visit - although I could feel tears welling-up at times.
Foundling Museum