Once you have finished sidequest 024 Miss Henny’s Misfortune, head back to Evermore to find that she has another sidequest for you there. She is trying to prepare a lesson for the children and wants your help in acquiring some mushrooms for her.

– “This is a very poisonous mushroom indeed. Expert knowledge is required to extract its venom.” - Answer is Toadstool
– “This refreshing mushroom tastes just as bright and breezy as it looks” - Answer is Bluesky Buttontops
– “This mushroom may look sweet and beautiful, but its flavor is famously awful” - Answer is Cutesy Pops

You can pick up Toadstools and Cutesy Pops from the Forest of Niall, but the latter are a lot rarer than the former. Cutesy Pops seem to be a little easier to obtain in the Hard Woods section, though, which unlocks a little later in Chapter 5. Bluesky Buttontops can be obtained from Makronos, once you gain the ship, but it might be easier to get them from the Branching/Spreading Lumberyard in Evermore, once you’ve leveled it to two.