Originally posted by FissionChips:

??? GreyDwalves 100% drop rate eyes, never seen less modded or unmodded.

According to the wiki its a 50% chance for 1 eye for a no star grey dwarf of any kind (except the brute its a 50% chance for either none or 2). I did a quick black forest night run and came back with 31 rocks, 31 wood, 31 resin, 20 eyes, 2 ancient seeds, 2 dandelions, 3 bukeperries, and no trophies.

I never really paid attention before I always just stored what I needed and obliterated the rest. It might have been changed with Mistlands.