Story mode, 2nd week or so.
Slime Liver from Crowned Slime.
Charred Lizard from Reginald Drisby (the rat boss).
Bat Wing from Eyeball-bats.
They're all in the Jade Way dungeon, I think.
The first 2 are easily gotten through boss rush, the last one is easily gotten by hanging around a floor with eyeball bats until one drops it.