Old beat-up wood is a personal favourite. One of my greatest misgivings about building new was that we would be working with new materials. But, given time, I've found ways of making the place look older than it is. More wizened. When I stumbled across an old wood pallet behind the garage, for example. I remembered seeing this:
And we got to work. It was really muddy, and huge & ungainly. But we wrestled it into shape by prying off certain board and replacing them in structurally-sound places. And up it went onto our bathroom wall. It was so fun to collect narrow-enough items to perch on the "shelves."