I'll tell you my 2 worst as I'm not sure which one I concider worst.
1) I was schooling an RDA horse in its home arena. I don't actualy remember much of the fall but my mum who was watching has told me what happened. I came out of a corner in shoulder in (that is the last thing I remember) and the horse bolted. He attempted to jump the arena fence and didnt make the top bar, resulting in him summersaulting. Unfortunatly it is the only time my superglu bum has ever gotten me in trouble as apparently I stayed on him and ended up under him. He scrabbled around on top of me whilst trying to get up and either stood on or kicked my head (we are not sure which but there is a very deffinate hoof print on the hat). I was unconcious for close on 20 mins, I was taken by air ambulance to A&E with a suspected broken neck, I spent the entire evening being scanned from head to foot, had a very nasty gravel rash on my arm cleaned out but was finaly allowed to go home having crushed 2 discs in my lowever back but done no other damage to my spine. I had a monster concussion and the only reason I was allowed home is because my mum is an highly qualified nurse and was able to keep an eye on me.
My helmet saved my life.
2) Was the first time I attempted to ride Reeco at a show, I was stupid and he wasnt ready. I went to get on him and as I swang my leg over his back he freaked and bolted whilst bronking. I hit the deck hard on the top of my head and summersaulted over, resulting in anouther horrible crunching sound from my neck and me fainting. I came round within a minute though but it resulted in anouther helicopter trip to A&E!!