I don't know, also a newbie, but I know that a lot of species of birds depend on diet for feather color, especially beta-carotene. Just as an experiment, try feeding her grated carrot. When I was a little girl, the flamingos at Knott's Berry Farm were nearly white. Turns out in the wild, they ate a lot of brine shrimp, and that carrot was a good substitute, and after that was added to the flamingos' diet they turned pink again. If it doesn't darken the eggshell, it will still be good for the chicken, and egg-color has no relation to the nutritional content of the egg anyway. It's just fun to have colored eggs.
Interesting. Chickens do not change the color of their eggs (other than fading). Colored ear lobes on a chicken mean colored eggs, white ear lobes is white eggs. Can you post a pic of one of the white eggs next to a brown egg? Maybe it is just faded tan. Both BO's and Del's should be laying brown eggs. Do you have any other birds like ducks around,.