Hmmm, let see...
pennies, ice cubes, cups, soda bottles, a brick, rocks, squirrell poop, bird poop, snot rockets, the innards of one of the forks on my shock when it blew up mid-air (thankfully not on the landing), another cyclist getting used to her clipless pedals, rabbit innards splattered by a car, a truck who's operator said he didn't see me though I was directly in front of him, wearing bright yellow, when he hit the gas (I had right of way, he was stopped at a stop sign). And hands from passengers in passing cars (twice).
That's all that comes to mind at the moment.

PS. Squirrell poop is a yellowy brown and thicker than bird poop, could this be it?