Mystic Eggs are items in Paper Mario: The Thousand-Year Door.
These items are found in the Great Boggly Tree, but they cannot be obtained until a little later in the game. Mario can find Petuni, a female Puni in the beginning of the tree, after Chapter 2 is complete and ask her if she needs to do anything. Petuni will give Mario a very small quiz called "Stump Petuni." Once solved for Petuni, Mario will receive a Mystic Egg. This egg will heal Mario's HP by 5 points just like the Egg from Paper Mario . This item is used in many of the recipes the first egg was as well as new ones that this game adds in.