To gain access to Maid Midgewort's lessons on potion brewing and wand crafting, you need to first perform a quest for her.
The problem is that the level range of the quest is low so high level PCs are effectively locked out of the lessons.
The level range she has in her description is for a lowbie quest she also gives.
It has nothing to do with getting her the pink mushrooms.
Remember you have to be a ponds citizen before you can access this!
Thanks for clearing that up!