To get the mask trading sequence started, enter the Happy Mask Shop in Hyrule Town Market and borrow the Keaton Mask from the Salesman for 10 rupees. At the base of Death Mountain in Kakariko Village is a lone guard. Speak to him and he will inform you his child has been wanting a Keaton Mask. He will pay you 15 rupees for it.
Go back to the Happy Mask Shop and pay 20 rupees for the Skull Mask. Now head to the Lost Woods and find Skull Kid. Jump up on the rock and show him the mask, he will pay you 10 rupees for it.
The third mask you get from the Happy Mask Salesman is the ReDead Mask. It will cost you 30 rupees. Inside of the graveyard is a small child who wishes to be like Dampe and be scary. Offer him the mask and he will give you 30 rupees.
The final mas in the sequence is the Bunny Hood and it will cost you 50 rupees. Outside in Hyrule Field is a man who is running around. His typical path is basically a lap around Lon Lon Ranch. When he stops to breathe, put the Bunny Hood on and play the Sun’s Song. He will let you know how he has heard stories of the hood and will offer you 500 rupees for it.
After completing this trade sequence you will be able to borrow the Goron’s Mask, the Zora’s Mask, the Gerudo’s Mask and the Mask of Truth. The Mask of Truth will allow you to read the Gossip Stones.