A couple of books that scared the crap out of me as a kid:
Ghosts and More Ghosts by Robert Arthur. I checked this out of the Lauderhill Public Library again and again as a kid. I could never remember the annoyingly generic title, but I always remembered the creepy cover! I also encountered the scariest story in a different collection when I was an adult, under the title The Believers.
High marks also to John Bellair’s The House With a Clock in Its Walls. I shivered as I read this on a hot summer day.