Morel at Fieldlands Camp teaches you the Mushroom Cake recipe and asks you to help spread the word about it.

The Request

Talk to Morel at Fieldlands Camp to accept his request.

Give Morel a Springy Mushroom

Springy mushrooms can be found in various areas of the Obsidian Fieldlands. Talk to Morel after you have at least one, and there will be a cutscene. You'll receive 5 Cake-Lure Bases and the Mushroom Cake recipe.