Leaving aside things like washing lines, digital TV cables etc, what's the thing you most regret hitting with your hedgetrimmer? I was cutting an overgrown privet hedge for a one-off customer. It was one of those that's had a chequered history, i.e. not been maintained professionally or even cut regularly, but just been been hacked at occasionally and pushed about and jumped on by the chimpanzee owners. Trying to cut the hedge straight for probably the first time in its life, my hedgetrimmer blades hit something hard and immoveable inside the hedge. The blades, hitting something they couldn't cut, tried to loop the loop, and I was left with a gaping quarter inch of daylight between the two blades at the end between the last two fixing bolts. I peered inside the hedge to see the offending article - an iron bedstead, complete with springs and castors, that had obviously been shoved in there at some time to fill a gap. Nowadays if I get called to view a garden and it looks like a bomb-site, I tell the client I only do "civilised" gardens and walk away.