In 1983 Atari buried cartridges with its unsuccessful game E.T. Some of the buried cartridges were recovered in 2014, covered by the documentary “Atari: Game Over” (produced by Microsoft).
Atari is not the only company doing this. In 1989 Apple buried a batch of Lisa computers they could not sell. Apple Lisa was the predecessor to the Macintosh. The site is a landfill in Logan, Utah. When will anyone try to recover computers from that place?
ArsTechnica: E.T. cartridges buried in New Mexico
USA Today: Diggers find Atari’s E.T. games in landfill
IMDb: Atari: Game Over