Apple

Apples are a fruit that appears in various games. Usually as a consumable by Sonic or a large prop in various games.

Sonic the Hedgehog (2006)
Apples can be found around Castle Town usually in barrels. They can be pushed by walking into or attacked to kick away. Silver the Hedgehog is able to use his psychokinesis to pick up apples and throw them as projectiles.

Silvers first Town Mission is helping Paganini put apples in barrels for the upcomming Apple Festival that is celebrated in Soleanna.

Sonic Unleashed
"It's yummy but kinda hard, I wonder if it was still a little unripe..."

- Chip, after consuming an apple.

The fruit itself was also available in Sonic Unleashed, it can be purchased for thirty Rings at various shops such as Counter of Dreams 2, Treeshade and Wang's Emporium. It is a consumable. It can be given to Chip to contribute to the BFF's  or to Sonic for the Hungry Hungry Hedgehog  Achievements/Trophies.

When consumed by Sonic, it will give him twenty Exp.

Sonic and the Black Knight
Apples appear in Misty Lake exclusively to the tutorial missions. They're collected like Pearls, even making the same chime sounds when collected. Unlike Pearls apples do not serve any purpose when collected other than for the player to practice with Wii-mote controls.

Sonic Lost World
Gigantic apples can be found in Tropical Coast. Master Zik uses them in his battle to roll over Sonic.

Trivia

 * The Apple Hat is available in the Black Market in these various games and can be purchased as a mask for your Chao to wear.