Dont know where you live, but if you happen to live in the Netherlands you can use:used traintickets.
Easy to get and free
Just hold them next to homey, and it will trigger a flow.
I have made several flows for my kids (and wife ,-) ) so they can easily trigger flows
You need to create a flow 1st to read the ticket. After that use that code to trigger a flow
See pictures
Flow to readout the card
Flow using the card
