Not a clue!

This little rockery plant is one of my favourites.  It pokes its head into the air and lets the passing winds jiggle it about.  It dances in the lightest breeze.  I bought it and three others for £1.50 in a plant shop near Aberlady about 25 years ago.  It's seen life in three gardens and now having remained undisturbed since 2000 it's thriving.  It's been split twice and now we have about 2 sq metres of it in the borders.  I haven't a clue what it's called (I know Knottman will and no doubt others).  I like it because it's beautiful.  Anyway, what's in a name.