Mine will run-away from "the new thing" for a while, until one gets brave and checks it out. Did that with some mushrooms I quartered and put in the brooder.
If you want to see a chicken-stampede - mealworms.
Check out the "Treats Chart." Also look at the bottom for things to avoid.
My chicks didn't know what to do with a tomato other than "walk all over it." However, they inhaled grapes, love lettuce, and will play with the core from bell peppers. When we prepare a salad, all of the veggie...