For raw vegetables, I love avocados, peppers, carrots, and cucumber. I'm not entirely sure why ... I think I enjoy the flavor and they contain enough water that I don't need to dip them in anything.
I'm not a fan of anything else plain, due to flavor or texture.
If you have a fridge, you can make a great salad with corn, beans, shredded cheese, peas, peppers, tomatoes, and green onion on either a spinach, lettuce, or cabbage (or perhaps a mix of 2 or all 3) base with ranch dressing. I make my own ranch dressing by filling a container about 1/2 of the way with plain yogurt, 1/4 of the way with mayonnaise, and then adding salt, pepper, garlic powder, onion powder, lemon juice, and dill to taste, and milk to your preferred consistency (if a veggie dip then you'll want a thicker consistency, and if a salad dressing you'll want a much thinner consistency).
Another good salad that would not require a fridge is chopped up apple or pear with a spinach base, walnuts (or any kind of nut honestly), craisins, and then for dressing equal parts balsamic (or apple cider vinegar) and olive oil, along with maple syrup to taste. I also like to sprinkle chia seeds on top.