When you bag your trash and bring it out to the curb for pick-up eternal storage in a landfill somewhere you normally think it's just that: eternal. But there's no reason to think that the landfills of today will be inviolate in the future. They're absolutely jam packed full of useful rare metals and materials. I think eventually garbage mining will be a common practice.
In Vernor Vinge's "Rainbow's End" they have this book scanning machine that just shreds the books then scans all the sheds super fast as they fly by and reassembled computationally the documents (like how DNA is read). Sometimes I worry about a future where this is possible with garbage and garbage mining is happening. Not only would a garbage mining company be able to sell the materials but the vast amounts of detailed very personal information stored discretely in each person or family's bag would also be invaluable. There would be economic motives to automate information retrevial from landfill garbage mining.
Depending on how far in the future this happens it could either be a privacy nightmare or a cultural treasure.