Somethings you burn in your fire could be dangerous so you should be aware of what and what not to burn. There isn’t much you can safely burn without making dangerous fumes. It is safe to burn any untreated, unpainted wood without nails (this would be your regular firewood). You can also burn twigs on the ground of your campsite. It is not very good for the environment if you burn paper or cardboard. You can burn some paper to get your fire started but when you burn paper it will break up and fly out of the fire pit. If you are in a really dry area there is a small chance that these ashes could start a fire but, check your campgrounds rules to see if they allow you to burn paper and cardboard. It is not safe to burn plastic, rubber, garbage and glass. Some of these things can create toxic fumes and those are not good for you or the environment.