Finding a stone with a hole in it is supposed to be lucky.
Well, taking a stroll recently, I found a nut on the ground. Of the metal variety, not the edible. This, to me, would seem just as good as a stone, if not better. In the modern world we're constantly in need of luck with machines, after all. The fact that it is man-made in my mind makes no difference whatsoever. (For what is Man but an implement of nature, after all?)
This seemed a particularly interesting coincidence, since just recently I've been pondering the potential of modern day heroes in spirituality. And, related to that, devising a simple pentagram ritual calling upon a few of my favourite pop culture heroes. The character I picked for north/earth (for reasons that may or may not be obvious) was Kaylee, the mechanic from the sci-fi show Firefly. I was also considering what kinds of symbols or items could represent these characters in a ritual or on an altar. As it happens, one of the items I thought of for Kaylee was... (drum roll) a nut.
So I picked it up, of course, and put it in my pocket.
There is probably no limit on what could these days qualify as a lucky charm, altar figure or other magickal item, apart from the imagination. Such things as computer chips, little toys, pop culture merchandise etc. spring to mind. As long as there's some connection (in your mind) with the item and a powerful concept or being, it should work just fine.