It would be cool to use the Leaves of the Dreaming Tree for something other than crafting druid-related weapons. I'd suggest that these are used as the main ingredient for 2 different brews:
1: Herbalism crafted poison drink. (negative)
Craft with: Leaves of the Dreaming Tree + Water + Honey
Result: A sweet drink with consumption resulting in restless sleep (sleep condition + negative % rest meter drop). DC could be consistent with whatever other poisons.
2: Herbalism crafted sustaining drink.
Craft with: Leaves of the Dreaming Tree + King's Crown + Honey
Result: A sweet drink with consumption resulting in restful sleep (well-rested related bonuses? + positive % rest meter)