"You got the Rupee Medal! While you're carrying this, Rupees will mysteriously appear more often. Keep it with you when your wallet feels empty!"
The Rupee Medal is an item from Skyward Sword. As long as Link has it in his pouch, more Rupees will appear from grass, enemies, and other sources. There are two available in the game. Both must be obtained by unlocking Goddess Cubes on the Surface and then returning to The Sky to find the corresponding chest.
The first Rupee Medal's Goddess Cube is found in Faron Woods after Link receives the Water Dragon's Scale. Link can drop down off a ledge on to a platform, which then connects to the area the Goddess Cube is on with a thin rope for Link to balance on. The medal can then be found in a Treasure Chest inside the Thunderhead, to the northeast of the Isle of Songs.
The second Rupee Medal requires the Clawshots. In the Deep Woods area of Faron Woods, Link can find some vines growing on top of Skyview Temple. If Link uses his Clawshots to climb up to them, he can reach the Goddess Cube. The treasure chest containing the Rupee Medal can then be reached by sleeping in Beedle's bed in Skyloft and then climbing the ladder next to his house, which leads to a small alcove for the chest.