Crop circles. We have all seen at least one on the internet.
Aliens
UFOs
watever
I have a new explanation! alright alright, get this:
Time-Traveling graffiti artists from the future
yeah
evolved humans from the future with the ability to travel through time. Maybe some of them aren't just artists, maybe some are just bored and felt like traveling to the mid 1900s to fuck with our minds.
Anyways, that's it.. interesting? you be the judge...
oh god, that last line was so tacky.