Michael Dahl 
Monster in the Letter Box [PDF ebook] 
And Other Scary Tales

Dory is brand-new to her neighbourhood, so it’s a good thing she has a pet monster to keep her company. When she tells the mailman about her monster, he doesn’t believe her. When Dory begins to get angry that he’s not taking her seriously, she opens up the mailbox to show him the monster — only to find that the mailbox is empty! Is Dory’s monster real, or part of her imagination? Find out what happens to Dory, the mailman, and many others in this collection of spooky stories.