I give mine live mealworms. I also have a bearded dragon that loves them so I raise them in a Tupperware container underneath his tank. During the winter I throw a handful of scratch into their coop in the evening, and the rest of the year they get weeds, strawberries, and pretty much anything...
I've heard that Apple and tomato seeds are toxic to chickens. I give cut-up apples to my flock if I've made salad for the bearded dragon, but even then it's been cored so no seeds. I don't give them tomatoes at all (because I'm not going to the trouble of seeding a tomato) but I'm sure they...