8 brainstorming riddles to sharpen your mind

Challenge your brain with these clever riddles. They may seem simple, but they can stump even the sharpest minds.

What has a bed but doesn’t sleep? A river

What turns white when it gets dirty? A chalkboard

What is the thing in your pocket that keeps it empty? A hole

What starts with P, ends with E, and holds thousands of letters? A post office

What begins and ends with E but contains only one letter? An envelope