My two week old chicks are eating bugs (grasshoppers & crickets), wild strawberries, cheerios and chopped hard boiled egg. Keep in mind that they will need grit once they are eating things other than their chick starter. For now I'm using parakeet grit, the kind without added calcium. Once they are going outside on a more regular basis I know they will find their own grit.
Oh and I also occassionally dig up a clod of dirt and throw it in the brooder for them to have fun with. I remove any long roots that they may choke on.
I forgot - expect them to be afraid of new foods. Just leave it in there with them for awhile and they'll overcome their fears. Also, another great treat that my big chickens enjoyed as chicks was millet strands (the kind sold for parakeets). I started taking the seed pods off the stem though after one little piggie tried to eat the whole stem.