My first fall was on a quarter horse that I swear everyone who rode him came off. I had asked for a trot, he took two steps, and then bolted. I rode him out for a while (even though I'd somehow manage to lose a stirrup), but his hind end slid out from under him. I flew over his left shoulder, slammed my head into the ground, and promptly got up. Got on a different horse since I felt fine, and after that checked my helmet. It was shattered. Had to get a new one before I could ride again, of course.
My worst fall was July 3, 2013. I was riding my green broke 3 year old in a new saddle, and she was being fairly good. Was getting ready to ask for our last canter depart, when the barn owners started a lawn mower. She flew forwards and to the left. I became unbalanced and fell right. Ding dong that is me tried to catch myself. I bent my arm backwards, severely dislocating my elbow and rupturing my artery. My husband held pressure on it from my landing spot all the way to the hospital (ambulance guys tried to splint it since we thought it was broken, but it caused it to bleed again). He did such a good job holding pressure I didn't need a blood transfusion.
I JUST finished PT on my arm, and while I don't have full range of motion I have it close enough. I was just cleared to ride again, but since we're expecting number 2 I can't really ride. I will get a pony ride today for the new year though ;)