Hee... my friend mows them down in her backyard all the time. It's frustrating that you usually have to mow over them twice before they'll get crushed up though - mow over them the first time, and you've just succeeding in knocking them over... once the mower goes past it, it just pops back up again to mock you. o_O and yes, I've seen thistles taller than me... I'm 5'3" ...they sure are pretty though. B)