Golden Feather

The Wind Waker
The Golden Feather is the spoil of the Peahat, the Winged Mothula and the Kargarok in The Wind Waker. If 20 of these are given to Hoskit on the second floor of Dragon Roost Island, who wants to give them to his girlfriend as a gift, he will give Link a "Thank You" letter and eventually a letter with a Heart Piece inside in return. "A certain strangeness emanates from this beautifully shining golden feather. Winged girls are said to be fond of these treasures."

- Inventory description

Phantom Hourglass
These feathers make an appearance as a treasure in Phantom Hourglass as Helmaroc Plumes. Described as flamboyant feathers dropped by Helmaroc Birds, they can be sold on Mercay Island to the Teller of Treasures for a fixed, random price. They can also be sold to a man on the Ho Ho Tribe's Traveling Ship for more an unfixed random amount, sometimes than 100 Rupees each.