Riddle Fun!

What room can no one enter? (answer below)

I think riddles can be a lot of fun! They can be silly, or challenging, and often they are a tricky play on words. Our family enjoys riddles! Sometimes we have “Riddle Fun” dinners in which everyone, young and old, brings a riddle to the table.
“Scientists get to solve puzzles every day, because science and research involve finding solutions from the clues that we are given. Just like with brainteasers (or brain teasers) and riddles, the answers to science mysteries are not always easy to see at first. With time and effort, they eventually become clear.” From NIEHS website

National Institute of Environmental Health Sciences has hundreds of riddles and brainteasers you might enjoy sharing with friends and family members.
Try this one: What can travel around the world while staying in a corner?
Answer: A stamp!
Now, what’s the answer to the riddle above?
A mushroom!