I agree with Aeshna5, Nettle leaved Bellflower which if your not familiar with the flowers are blue and look a bit like foxgloves!
I planted a couple of Cirsium Rivulare Altopurpureum in my borders last year as a beneficial insect plant as well it's charming looks but as soon as the flower heads started to show they mysteriously where knocked off! I think it's either the pheasants or the once domesticated American Wild Turkey's which where set loose around the time of the bird flu doing the damage I'm not sure (whoever caused the damage must have found the bright flowers too much to resist)! I completely forgot all about that and must go check to if there's any new signs of life!
Cheers
Jez