Waterfall Hut Side Quest
At the start of the game, on top of the hill which houses the very first dungeon you'll find an old man in a hut. Speak with him and he'll tell you that he left his Tool Bag next to a tree with red leaves that's east of his hut. If you leave the building the old man is in and look to the east, you'll be able to see the tree that he is talking about.
Head on over to that tree and pick up the Tool Bag that's sitting next to the trunk; a screen shot of what you're looking for is shown below. Once you have the Tool Bag in hand return to the old man with it. You'll be rewarded with 8 Plain Cheeses for completing this task.
Inside of this Old Man's house search the bags on the wall to find an Agility Seed. Depending on when you're reading this it's also important for you to remember what these bags hanging on the wall look like. My first play through of this game it didn't occur to me that you could search these bags, causing me to miss many hidden treasures like this Agility Seed.
Later in the game you can return to this Old Man and collect even more rewards from him.
After Acquiring the Ship: 4 Mild Cheese, 2 Cured Cheese and 2 Angel Cheese
After Visiting Dragovian Sanctuary: Return for a special scene