When you reach the shores of the Zora River after completing the Great Deku Tree and Dodongo’s Cavern dungeons you will run into a heavy set man known as the Bean Seller. He is seated in front of a metal gate.
Speak to him and he will offer to sell you Magic Beans. The Magic Beans can be placed in the various mounds of soft soil that you can find around Hyrule (shown in the screenshot below).
The Magic Beans are fairly expensive. They start at a reasonable price of 10 Rupees and then increase in price by 10 Rupees each time you purchase them. There are a total of 10 Magic Beans that you can buy off the Bean Seller, which means that you have to spend a total of 560 Rupees in order to get them all.
There are 10 locations around Hyrule where you can plant the Magic Beans in order to obtain various rewards. The planted Magic Beans will transform into a leafy platform once you return to each of the areas 7 years later as old Link.
1) The first spot is right beside the Bean Seller.
2) In the Kokiri Forest near one of the huts.
3) Inside the Lost Woods near the bridge to reach Hyrule Field.
4) Inside the Lost Woods near the Business Scrubs.
5) In the Graveyard of Kakariko Village.
6) At the entrance to the Dodongo’s Cavern.
7) In the Gerudo Valley down near the river.
8) Near the Lakeside Laboratory at Lake Hylia.
9) Near the Warp Point inside the Death Mountain Crater.
10) Near the entrance to the Spirit Temple.
