This was also a strong subplot in Cast Away, both in plot and theme, with the FedEx package with the winged-hearts that Tom Hanks eventually returns. In fact, a package with the same kind of symbol (a sister package) opens the film and the film wraps with the delivery of the special package and Tom wondering if he should go after the woman who sends them.

(Oh - this got me thinking about some of these ideas. How they can function in different ways in a story. Not only as the key concept or driver, but a subplot or even resonate in a thematic way; the lightning one from yesterday did something similar, as it brought to mind the ideas of luck and fate.)

You could also go Sliding Doors on it, explore what his life would have been like had he not lost the wallet verses what it is. Maybe there was a winning lottery ticket in there or his dream girl's phone number or a valuable rare coin. Or it could have just affected the timing of his day (as in does in Sliding Doors).

You could do some interesting things with that. Someone write it and let me read it.

This type of scenario could makes for a great horror movies, with a protagonist discovering either literal or metaphorical "skeletons in the closet."

Oooh I liked this plot point in Amelie, discovering and returning the tin of childhood treasures. The man's surprise in the phonebox chokes me everytime. This leads her to help others, which she perceives to be her life's purpose. I also like the reveal that the treasures were not so innocently used, as Amelie imagines.