I didn't have a broken spoke or even an untrue wheel at the time, but a couple months ago I was riding a nearby stone dust bike path and mysteriously crashed. The last thing I remember was running over a stick, which I've done many times before (my hybrid has 700x35c wheels and I usually have no issue). Picked the bike up and found the rear v-brake lodged in the wheel. Still unconfirmed, but I'm guessing what really happened was when I ran the stick over, the knobby tires in the rear grabbed it, knocking my balance out of whack and caused me to fall. I probably will never find out how it happened, but I managed to get back on the bike and finish off the 30 mile ride (~15 miles left) slower than usual since my knee was in pain from the fall.