Consider magical treasure in stories and roleplaying games, and under “magical,” I’d include science-fictional stand-ins like laser guns, lightsabers, and matter replicators. As you may have gleaned from television, games, and books, the ruins of longstanding magical or high-tech civilizations crawl with monsters or mutants who keep a few sorcerous items. The magic is usually rare, and more or less straightforward: swords (or the lasery equivalent), rings of invisibility, wands, blaster pistols, and that sort of thing. Generally, their function is obvious or easily blundered upon; a chimp could work them out.
But if you think about it, maybe this is backwards. Rather than being rare and straightforward, maybe arcane treasure would be ubiquitous and baffling. You’d find it everywhere, but it would be useless without the instructions to go with it.
Magic lacking feature documentation has a tradition in science fiction and fantasy. Those of us around in the eighties will remember The Greatest American Hero, a cheesy sitcom about a superhero who lost the instructions to his alien suit and discovered a new feature of it every week. (This was inconvenient for the hero but very convenient for the writers, who could come up with a problem and a power to match it five minutes before deadline.) And in The Lord of the Rings, there’s one of those straightforward magic rings of invisibility, but it turns out that, like your smart phone, it can do things you never would have dreamed of, such as enable you to command the bearers of other magic rings. (Yes, your smart phone can do this; the instructions are lost and buried in the vaults of Minas Apel.)
But there doesn’t seem to be much of a tradition of ubiquitous magic, and that strikes me as odd all of a sudden. Garages all over the first world are troves of magical appliances lacking instructions. And many of them are anything but straightforward. You can find videos online of kids trying to work out the functions of 1980-vintage computers, with amusing results. Granted these jaded little monsters find the technology quaint, but those excavating the ruins of the Post Apocalypse one thousand years hence will literally kill for a machine that adds up two six-digit numbers in under an hour — let alone a smart phone, a first-generation plasma rifle that looks like a doorknob, or an Oculus Rift, which will all be similarly out of date by then.
And if a society produced arcane rather than tech devices, it might likewise accrete stores of obsolete treasure. Heck, if memory serves, the Melniboneans in Moorcock’s Elric Saga had been doing sorcery for ten thousand years. The streets must have been overflowing with confusing gewgaws tossed out by bored effete wizards over that period.
Maybe the real treasure of the future will be User Manuals. You get ahold of the right user manual, and suddenly the stuff you find on a sewer grate takes you from pauper to prince.