Where can I find elemental fruits?

From the stickied topic post on the kameo board

Obtaining Fruit is done in six ways:

a) Find a plant with an Elemental Fruit on it. Approach it, and press A to shake the Fruit loose.
b) Find it hidden randomly in areas. Look under the rotating plants, in hanging pods, under shells, or in chests, jars, or ice blocks.
c) Help NPCs (Non-Player Characters) in any way you can. Their reward for helping them is usually in the form of a Large Fruit, which is worth 3 Fruit to your tally.
d) Complete a Sign Quest in one of the four areas (Enchanted Kingdom, Forgotten Forest Glade, Mountain Falls, and Snow Top Village). Each area has a single five-sign quest, like a treasure hunt. Simply follow the clues to the next sign. The fifth sign will yield a Fruit.
e) Some enemies and challenges bear fruit, such as the Water Trolls in Treasure Cave, or Typhoons Quiz in the Enchanted Kingdom.
f) Complete one of the Warrior Trainers Challenges in the Lost Ruins. You can only receive one fruit from each Challenge.