Its noun meaning: lack of complication, clearness; candor, artlessness; plainness in manners or way of life; silliness, folly.
I chose these eggs to represent simplicity because of their simple shape yet colorful palette. I also loved the meaning of plainness in way of life. It makes me think of "little house on the prairie" days which seemed so much simpler than our world today. At least the tv version anyways :) Although I can't imagine having chickens or collecting eggs, I sure do appreciate their beauty.