When selling items to Temmie, if she seems to really like it say no to get a higher price. You can purchase items from the Turtle shop in Waterfall and walk them here for a profit, or you can sell Dog residue infinitely to the Temmie. This is home to the temmies and also the best shop in the game as it's the only one where you can sell anything. Once you've lit up all the mushrooms in the dark section in Waterfallhead on the southern path to find Temmie Village. IGN's Undertale cheats and secrets guide gives you the inside scoop into every cheat, hidden code, helpful glitch, exploit, and secret in Undertale.