Yesterday I went to make something and I cracked open two eggs and both yolks were an odd greenish/darkish color. They were fresh eggs, I gather eggs each day. I smelled it and it smelled fine. This was not a rotten egg. I threw them away and I cracked open two more eggs of which were also fresh (I ended up cracking open 8 total) and all of them had this same freakish color to them. I live on the northern plains where it has been bitter cold. My chickens have not been going outside except on a rare day when the sun is shining and it's "warm" (relatively speaking). Otherwise they'd rather not be in the snow. I haven't changed their feed. They get chicken feed from the local farm and home store that I have always purchased. I also supplement them with cracked grain which I also purchase from the same store. There is nothing else that they have access to. They get fresh water every day. We pick their eggs every day. The one thing that I have done differently in the last two weeks was to take a small Walmart sized bag full of shredded paper and tossed it into their coop. I've been considering getting shredded paper to use as bedding and I had this small bag of it and just threw it in. (No, I did not leave the walmart bag in there). Today when I cracked open the eggs that were gathered from today, they still have an odd greenish tinge to them, but it's getting lighter colored. Any thoughts or ideas?