The two main flying wings are the Northrop N-1M and the Horton Ho-229.  It seems the Northrop N1-M drew huge lessons from the Horton Ho-229. Or did it? This one apparently dates to 1940. Northrop's first flying "wing" had twin booms and a conventional tail. But this one was a genuine flying wing. The Northrop was a major step to what would eventually become world's most expensive plane, the modern, stealth B-2 bomber.