Chuffa plant...its the ones Turkey hunters plant to draw gobblers in to their land.
Over seas the nuts are called tiger nuts , but in the USA you can find them under Chuffa nuts.
Or just go to one of the carp tackle shops in the USA and look in the bait section for Tiger nuts.
I personally have tried them and they failed horribly and have stuck to what works for me , but know others that use them and catch...so good luck if you get some to try.