I have had several of these egg this winter too. I don't know which hen laid them as I have 20 and they lay in each others nests, I can't tell you why but it's a first for me too.
I know that this is an old thread but thought I'd throw my 2 cents in. I feed my chickens milo. I mix it in with their scratch feed. They eat it first, picking it out before anything else. They love it. It doesn't seem to have hurt them any, I don't know if it is bird resisant or GMO. I buy it...
Thanks Junebuggena that makes me at least 9 roosters out of my 50 odd chickens that need to be culled. I have 2 older roos I want to keep and several younger roos that need to mature more before culling. These are some of my chickens. The rest are out running around.