You can imagine my surprise when I had a hen lay a clutch of rainbow colored eggs. They vary from pink to blue to bluish-green. What causes this? Are they safe to eat? I thought eggs came in only white or brown. Ive never seen pink eggs or blue eggs for sale anywhere. I have heard of easter egg chickens laying colored eggs, but my chickens are just mutts as far as I know, and their mothers certainly never layed colored eggs.

They are perfectly safe...exactly the same as the white & brown eggs you are used to, just a different shell color. One hen is not laying all of those eggs since there are different colors, but several hens may be using the same nest. If their mothers did not lay colored eggs, I would guess that their father must have been an Aracauna or Americauna, which are the 2 breeds that lay colored eggs. It is a dominant characteristic, so even if you hatched your birds from brown eggs, they would lay colored eggs. Do your birds have bunches of feathers under and around their beaks, or are they pea combed? Those are good indicators that they carry Aracauna/Americauna blood, but they don't necessarily have to have either to lay colored eggs.