If we are talking simple snacks and not prepped or cooked:
Rice Cakes
Fruit: Apple/Banana
Avocado
Veggies: Sweet Peas, Baby Carrots (w/PB or Hummus), Mushrooms, Peppers
Nuts: Pumpkin Seeds, Raw Almonds, No Salt Peanuts
Greek Yogurt
Granola
Those are just some you can pickup at the store...