Yes it is a fascinating subject.
I see mostly either trash or roadkill.

One thing I notice about the trash is that it seems the people throwing all this trash out of their cars are all consuming beer, cigarettes, soda, gas station coffee, fastfoodburger boxes, donut boxes, and chip bags. I NEVER see empty containers for such things as milk, real juice, yogurt, trail mix, sports beans, gator aid, banana peels, granola bars, or anything else even remotely nutricious. Do you think eating junk food turns people into slobs who throw garbage out their windows?

As to the roadkill...I live in the country, and there is a lOT of it. Very sad.
Now the cold weather is setting in, and all the dead frogs, snakes, birds, turtles, worms, and bugs are disappearing. Now it's more squirrels, possoms, racoon, deer, skunks, rabbit, mice, chipmunks. Riding my daily route, it's like an ongoing macabre piece of performance art watching new characters appear and the old ones slowly disintegrate and become mere stains on the asphalt.
Well, with the cold, at least my brakes aren't getting covered with flattened earthworm "ribbons" anymore!