HFF everyone (the fence is there in the background ... just visible!)
Cardoons are edible but I don't recall ever eating them in England (I do know they were popular in the middle ages and later). I guess they must have some similarity to their cousin the artichoke. They are eaten here these days in Spain; but I'm not sure what part of the plant is eaten nor how it's cooked. I suppose I should Google it. I'll report back later!
Got it! It's the stems of the leaves that are blanched and the end result is a little bit like braised celery (apparantly) www.youtube.com/watch?v=twVdHnc_IM8
Another roadside find.
Latest info Actually more likely to be MILK THISTLE, but very closely related to Cardoon and the French even call it Chardon Marie.