Within The Alola Region, there are many places where Pokémon will attack you through dust clouds, falling from trees, or flying overhead. After some of these battles, however, an item will appear which requires being picked up. Usually, these are valuable items that can be sold for high prices, competitive Battle items, or even special wings that can boost EVs. The appearance of these items are at random, so a player can always exit the area and try again to collect these items.
Dropped Items
Route 3 Flying Pokemon (Spearow, Rufflet, Vullaby): Pretty Wing & Sharp Beak
Poni Plains Flying Pokemon (Braviary, Mandibuzz): Muscle Wing & Genius Wing
Route 10 & Route 17 Flying Pokemon (Skarmory): Clever Wing & Resist Wing
Route 17 & Poni Plains Flying Pokemon (Fearow): Health Wing & Swift Wing
Hano Beach Sand Spots: Stardust, Star Piece, Comet Shard
Hano Beach Sand Spots (Sandygast): Spell Tag
Haina Desert Sand Spots: Black Glasses, Soft Sand
Cave & Canyon Dust Spots: Big Root, Soft Sand
Rocks (Riding Tauros): Stardust, Star Piece, Comet Shard
Poni Plains Shaking Grasses (Hariyama): Black Belt, Sitrus Berry
Lush Jungle Shaking Trees (Fomantis): Honey
Hano Beach Skaing Water (Tentacool): Poison Barb
Water Rocks (Riding Sharpedo): Stardust, Star Piece, Comet Shard
Catching Wimpod: Big Pearl, Nugget