What should I bring on a picnic?

I’m going hiking with a friend this weekend. We’re going to drive up to the mountains, poke around some nature trails and historic sites, and maybe go down to the river. She eats like a bird and I eat like a horse. I’m looking for some healthy, high-protein snacks that are ok to sit in the car all morning. Whenever we go on little trips together she always does considerate things for me, so I’d like to do something nice like prepare things homemade as much as possible.