In my town the accepted method to dispose of unwanted leaves in your yard is to rake them into a pile along the sides of the street. Frequently these piles are close to 3 feet high and stick out into the road at least that much. Street sweepers come by every few weeks and suck em all up.
So I was riding into work this morning and I was fiddling with something on my handlebars not really paying attention when I noticed I was about a foot away from plowing into one of these massive piles of leaf. So 15 mph I blasted straight through praying that some jerk didn't hide a cinder block at the bottom of the pile.
Leaves everywhere

all over the sidewalk, the road, me, stuck in my spokes, and my gear cluster....so much so that my chain started skipping

thankfully I stayed wheels side down with no trouble and continued on. And cleared out my rear cogs at the next traffic light
I love autumn riding.