I have read this whole thread and wow, egg eating seems to be way too common! I stopped my flock with mustard. But I did things a bit differently. I took two halves of eggshell from our breakfast and painted the inside of each half with spicy mustard. Then I simply offered it to the chickens. I instantly found out who the egg-eaters were because they all dove on the eggshells. But as soon as they got a mouthful of mustard, they shook their heads and scraped their beaks on the ground. I also took a natural-colored plastic egg and tossed it on the ground. Again they all ran for it. They pecked at it, they wandered off as they realized it wouldn't break. I repeated this several times a day until no one showed any interest in the eggs. I have ceramic eggs in the nests and gather all the fresh eggs several times a day. I also feed plenty of oyster shell. I haven't lost any more eggs.