This actually friggin' works. No idea why. Luck stat 7 (knight class with no investment in luck), Gold Serpent Ring +3, Symbol of Avarice, Crystal Sage Rapier LH and rusted coins gave me 423 item discovery. I farmed the two knights for 5 minutes (6-8 knights killed) and got 1 ear. I proceeded with quitting the game entirely, not just to the game menu, but all the way to the startup interface of the game system (I'm on PS4). I reloaded the entire game, repeated the above-mentioned and got 1 new ear after 5 minutes.