Trail mix, sometimes called 'gorp' (short for good old-fashioned raisons and peanuts) can be made with a variety of ingredients. The main ingredients in a store bought package are usually:
Adding some dried fruit to this mixture is a good idea.
Other possibilities include but are not limited to:
I'm also thinking granola or granola clusters from any granola breakfast cereal would be tasty also. Feel free to experiment with this recipe.