Drom Berries can be found in the courtyard of Delberg Castle, near the fountain house. They can be mixed with (used on) wine, ale, or spirits to create a mixture that can cause the recipient to fall asleep.
|Spoiler: The Princess must give a spiked bottle of alcohol to Thell Bennard in order to sneak into the Earl's rooms.|
Drom Berries, when eaten alone, have a slightly sour flavor and will cause discomfort in the belly due to "increased gas production". They can however be mixed with alcohol in order to create a poison of medium strength which causes its victim to feel drowsy, and even fall asleep.