It was a plain white raw egg. My husband found it just sitting there. My eggs are all colored. We are on county property, which is unincorporated, there aren't any laws that I know of about chickens. Lots of people have them here, along with all sorts of farm animals. We have nearly 3/4 acre and I don't hear them when I am anywhere except the yard where they are and on that side of the house. I do have really "different" people living nearby and many are really old....but I don't think they would even be able to hear the chickens where they are. The neighbors next to me, the husband doesn't like much of anything, he suffers for anger and depression anyway, and I give them eggs all the time. Their kids are over here all the time. We have so many wild birds here that make so much more noise than chickens.....like wild parrots, crows, and various birds of prey.
It is just odd, although I think maybe the kids did it as a joke. I am going to ask them all let you know if it happens again.