Well this is the thing. I read that they come from one of these / a / country that is not under the EU - whatever laws for import, but try Holland & Barrets, as I think they do them. Check also with your local (if you have one) Asian Supermarket! Furthermore, put it into Goggle and you'll get more infor on same!
I've noticed they are in lots of recipes at the moment, and don't remember seeing them before, Are they the leaves of pea plants? Do you eat them raw like lettuce?
Sorry to be so long in answering Jayne, I am in East Anglia. We are not usually top of the list for new things, so if we have it, chances are, you might too. Good luck. Elly.