Upon reaching the point in the storyline where you get the chests in the chieftess' hut at Woodburrow that the person refills every day, open the chests and grab the coins. Once done, go to the "Level Select" screen and enter a level. As quickly as you can, open the menu and return to Woodburrow. When you get back into town the chests will already be refilled. Repeat this process for infinite coins. This results in about 440 total coins and takes 30 to 45 seconds to repeat.