Extra green mushroom stuck in my inventory

I have a green mushroom stuck in my inventory. After completing the quest that required cooking 3 mushrooms in the cauldron, I found this one. It’s now stuck from a previous difficulty level, and I can’t drop, sell, vendor, or store it. Please remove it from my inventory as it’s taking up valuable space.

this!!!
It's so annoying and I don't want to redo the quest just to get rid of this!

You can't drop in town, but you can drop outside town.