Items can be obtained by winning bonus game and bandit battles. You can win one of several prizes which can then be used at any time during a level (except during boss fights). Up to 22 items can be carried at a time but in any speedrun of the game, items are purposely ignored, as they are always out of the way and simply not needed. Although, if you happen to get a bonus game they could prove useful
One of the more useful items, at least for 100% speedruns, the +10 star can be a quick way to recover stars if you get hit. If you're above 20 stars, this item (and the +20) will only give you stars up to 30.
Functioning the same as the +10 star item, the +20 gives you 20 stars and can bail you out if something goes horribly wrong in a speedrun.
If you're in a tight spot and need eggs, this item will give you a refill up until you have 6.
Acting as though you had just hit a POW block, this item will turn all the enemies on screen into stars. It is very similar to the big eggs seen in 2-7,
Similar to the POW, the winged cloud item turns all enemies on screen into winged clouds.
Not exactly a useful item but the watermelon can act as a replacement for eggs in a tight spot. Using this item is the same as if Yoshi had tongued a watermelon, allowing him to spit out seeds.
Acting as though Yoshi had just tongued a fire-melon, this item allows you to breathe fire 3 times. It can burn enemies to a crisp and clear the ice blocks in 5-3 if needed.
Allowing Yoshi to breathe ice 3 times, the ice-melon can freeze most enemies in place, which would then let you break them or bounce on top of to get an extended flutter.
Another not so useful item, the magnifying glass reveals all hidden red coins and winged clouds in a level. This would be a good item for a casual play-through but not for a speedrun (unless you forget where a red coin is in 100%).