The houses in the game are found in the village.
The first house on the left is locked and can never be unlocked
The third house can be unlocked with the key given to you by the squirrel.
The fifth house (next to the Forge) is empty except for several lollipops. Click the lollipop on the dresser to pick it up. Next click on the middle tassel on the right edge of the rug to reveal a lollipop. Finally, click the left handle on the dresser to reveal the last lollipop inside.
The Sixth House (on the far right) contains a quest that involves killing rats in a woman's basement. In this quest you MUST have a weapon else she will not let you undertake the quest.