I guessed walnut, we have been growing walnut trees for almost 30 years now. We are growing them to harvest for milling into planks to refine to build cabinets, furniture, trim. They are beautiful trees with nuts, but wear gloves when you peel off the green shell, as well as inner shell or you WILL have walnut stain on your hands. oh boy did I find out the hard way.
I'm sorry to hear about your experience. The first thing you get to learn about walnut trees as a kid is that you can't peal the nut without getting dirty, unfortunately.