My Guinea pigs' favorite food is dandelion greens. On nice days like this when we are home, we put them outside in a little pen so they can eat all the grass and greens they want. (I don't spray chemicals on my lawn, so it's safe to put them out there.) We go out and move the pen every so often so they get a nice fresh supply of weeds and grass to forage. Yup, they just love their dandelions.
Why, yes, I do have a paper I'm supposed to be writing. How could you tell?