I have several items that I have inherited from my father-in-law (post war and Williams Reproduction) and brother (Marx), and all the ones I've kept have sentimental value to me; they were trains we ran together.
The one that would classify as a Tin Plate oddity is a Lionel Prop Driven (actually wind up) Motor Car my brother would run around his small Marx layout. We had fun with this one. I plan to run it again soon.