Egg

Throughout the Marioverse, Eggs have many uses.

Yoshi Eggs
The spotted Yoshi Eggs are white with specifically-colored spots. These colors depend on the gender and color of the corresponding Yoshi. If the egg is from a male Yoshi, the spots will be the color of the Yoshi that laid it. If the egg is from a female Yoshi, the spots will be the color of the Yoshi inside the egg.

Yoshi Eggs are able to be used as projectile weapons--mainly by the Yoshis themselves. However, only Yoshi Eggs laid by females hatch into more Yoshis.

Birdo Eggs
Although recent discoveries have proven that Birdos can spit pink Yoshi Eggs, most Birdo Eggs are non-spotted. A Birdo will spit Birdo Eggs out of its cannon-like snout, and use the eggs like bullets.

Mystery Egg
Found only on Mt. Rugged, Mystery Eggs are from an unknown creature--most likely a Klepto, as they are common in the area. Mario only finds them in Paper Mario, and even then only in a bush near the train station. The egg recovers 5 HP, but is used in all sorts of recipes by Tayce T.

Mystic Egg
Found only in the Boggly Woods, Mystic Eggs are from an unknown creature. Nobody knows where to find them except the Puni girl, Petuni. For a certain favor, Mario can obtain Mystic Eggs from Petuni during the events of Paper Mario: The Thousand Year Door. Like in its prequel, the egg recovers 5 HP and may be used in all sorts of recipes.