Chestnut

Well, now I’ve learned something!  I thought that Gollum called the first riddle a “chestnut” because that might be an idiom for “easy to crack”.  I have been educated.  OED tells us:

 6. slang. A story that has been told before, a ‘venerable’ joke. Hence, in extended use, anything trite, stale, or too often repeated.

  • 05.032 Chestnuts, chestnuts,
  • 05.032 Chestnuts, chestnuts,
  • 05.041 This he thought a dreadfully easy chestnut,

“chestnut | chesnut, n. and adj.” OED Online. Oxford University Press, March 2016. Web. 2 June 2016.

Cavern

  • 01.073 To dungeons deep and caverns old
  • 01.077 To dungeons deep and caverns old
  • 01.082 and caverns dim
  • 01.083 in dark caverns.
  • 01.144 To dungeons deep and caverns old
  • 03.037 in the deserted caverns of the mines of Moria,
  • 04.022 when they stumbled into a big cavern.
  • 04.024 and dragged them to the far end of the cavern
  • 04.035 in the cavern went out,
  • 09.053 Leave the halls and caverns deep,
  • 11.008 and see the dark cavernous opening
  • 13.050 of the dragon-haunted caverns,
  • 15.026 They explored the caverns once more,
  • 15.041 Come back unto the caverns old’!