While searching the islands for a Big Heart, you may find an apple. The apple doesn't do anything at all, but it tastes good.
The Anklet will automatically enable you to jump two spaces instead of just one. It only works for the room you collected it in; once you leave the room you will not be able to double jump again, be careful. Like most items, you'll find it again in future chapters.
Chapter 6 Weapons
It seems as though aliens like to drop cleats here and there, but call them Spikes. With these, you can strike each enemy on the screen once(from your standing position), every time you use it. Of course, you can only use them so many times. You'll see these again in the next chapter.
The Astericks make great weapons. You can throw them and hit twice as hard, or throw them, then hit the B button again and split them on a 90degree angle in opposite directions. You will need to learn how to use these correctly for an upcoming boss.
Horse Hydes are just island baseballs. They are the only weapon that can be used on Broken Joe, so don't waste them until the boss battle!