We have a diverse flock eating a fully organic diet. We buy an organic soy free grain based feed which they have access to throughout the day, but they spend a good bit of the day looking for bugs and other natural foods growing in the yard. As a result the shells are a bit harder than grocery story eggs, and the yokes have a lot more color to them then what is typically sold in stores. Since our flock is diverse we also end up with several different colored eggs. My personal favorite are the blue shells, but we also get a few different shades of brown and even a few white.