Part of canal history - them, and so called 'Tommy Notes'. Payment to workers building the canals was often done with tokens such as shown, in lieu of real money, as the tokens could only be exchanged for goods in the 'company' shops or Tommy houses - often pubs - and for which the main contractor got a cut. Their real value was less than real money. You got paid in 'Tommy' or you had no job.
There are many good books available on the development and history of canals, one I would recommend you seeking out is by D. D. Gladwin 'The Waterways of Britain, a social panorama' ISBN 0-7134-3159-8 Amazon have it.
Edited to add:
"A Horse On The Cut" by Donald Smith is also very good, more than just about horses, or 'animals as some boat people called them.
Available from Amazon and Abe books.
Here we go! Even a song written about them: The Tommy Note!