The
Mushroom Planet novels are set on a tiny, habitable second moon in an invisible orbit 50,000 miles from Earth. The "Mushroom Planet" is covered in various types of mushrooms and is populated by little green people.
- The Wonderful Flight to the Mushroom Planet (1954)
- Stowaway to the Mushroom Planet (1956)
- Mr. Bass's Planetoid (1958)
- A Mystery for Mr. Bass (1960)
- Jewels from the Moon and the Meteor That Couldn't Stay (1964)
- Time and Mr. Bass (1967)