When the shape of the sun's disc in the sky changes as the moon eclipses it, shadows can get weird. That even happens in places that only experience a partial eclipse, like in the above image from Wisconsin.
As the moon's disc creeps across the sun, crescent-shaped shadows can appear on the ground in an ever-repeating mosaic. They're basically a pinhole projection of the eclipse, sometimes created by trees.
Shadows become even more eerie in the path of totality. In a phenomenon called shadow bands, long gray ripples appear and move rapidly along the ground or the sides of buildings just before and after totality. Scientists still aren't sure what causes them.