We have Jerusalem artichokes, but you don't see them very regularly. I had to google them to get a picture in order to remind myself what they looked like. I don't think I've ever eaten one, and having spent years working in supermarkets (both high-end and not so) I can state categorically that (in York at least) people do not buy Jerusalem artichokes with any regularity.

Yumm, brussel sprouts. Nom nom nom.