The Legend of Zelda: Oracle of Seasons/Trade Quest
You do not have to complete this trading sequence to get the final prize, but you shall at least giving the Mushroom to Syrup so that you will be able to buy potions.
Cuccodex edit
Earliest time: after 1st dungeon
Requirements: Ember Seeds
This item is found in the southeast corner of Horon Village. One screen right of the Ember Seed Tree, there is a house. Go in the house and light the torch inside. The man will reward you with the Cuccodex.
Lon Lon Egg edit
Earliest time: after 1st dungeon
Requirements: Cuccodex
Take the Cuccodex over to where Din and her troupe were at the beginning of the game, and go up one screen. Go into the house to find Malon. Talk to her, and give her the Cuccodex. You will receive the Lon Lon Egg.
Ghastly Doll edit
Earliest time: after 1st dungeon
Requirements: Lon Lon Egg
Hit Maple. Hitting Maple is not a random encounter. To make Maple appear kill 30 enemies (15 if you have Maple's Ring) and go out the Western exit of Horon Village. Go one screen below Hero's Cave (this is just one place where Maple appears, there are many other places where she will). You will hear Maples' theme, hit her and the Lon Lon Egg will fall from you. Maple will take it and give you the Ghastly Doll.
Iron Pot edit
Requirements: Ghastly Doll
Head towards Spool Swamp, but don't enter. There is a house one screen below the cliff used to enter the swamp. Enter this house instead of the swamp. Talk to the woman inside, and give her the Ghastly Doll. In return she will give you the Iron Pot.
Lava Soup edit
Requirements: Iron Pot, Roc's feather/Cape
Go through the portal to Subrosia you originally followed Rosa through. Go down the left staircase, and left two screens. Go down the stairs, and down another screen. Go left a screen, and hop over the lava going up one screen. Enter the house and talk to the Subrosian inside. He will pour Lava Soup in yur Iron Pot just for showing it to him.
Goron Vase edit
Requirements: Lava Soup, Zora's Flippers
Go through the secret diving spot in Sunken City and then head up the vines. Go as far west as possible until reaching a cave that leads to Goron Mountain. Get to the summit and talk to Biggoron to receive the Goron Vase.
Fish edit
Bring the Goron vase to the vase collector in Sunken City, and he will trade it for a fish.
Megaphone edit
Bring the fish to the old man in North Horon who is trying to get his cat from the tree. He'll swap the fish for a megaphone.
Mushroom edit
Back on Mount Cucco, find the cave where Talon is sleeping. Wake him up with the megaphone, and he'll leave, so that Link can get a mushroom.
Wooden bird edit
Bring the mushroom to the witch Syrup in Sunken City, and she'll trade it for a wooden bird.
Engine grease edit
Bring the wooden bird to the clockmaker in Horon Village, and he'll trade it for some engine oil.
Phonograph edit
Bring the grease to the musician in the east suburbs. He'll use it to make the windmill spin faster. As a thanks, he'll give Link his phonograph.
Noble sword edit
In Tarm Ruins, find the music-loving Deku Scub. Delight him with the phonograph, and he'll give a secret solution for the Lost Woods that allows to find the Master sword.
In a linked game, link may have already obtained the L-2 sword. In which case, the Lost Woods conceal the L-3 Master Sword.