I belong to a master gardener group in Jersey. Every year we have a Beach Plum festival.
I never heard of them either and actually have not yet participated, for whatever reason. I am hoping to go this year. It appears to be a lovem' or leavem' kind of fruit.
Everyone seems to have a ball and they bring them home and make some impressive jams and jellies from them.
I am lookijng forward to this years bounty and the fun that goes along with the 'picken'.