Not true - although we know about Jack Northrop's obsession with flying wing designs, by the time the B-2 was on the drawing board he had been long gone and Northrop Aircraft was a way different company from when he ran it. A flying wing platform was chosen more as a matter than function rather than previous designs or Northrop's design legacy. Having worked on the B-2, I can tell you that many of the people who ran the B-2 program probably never heard of the XP-56 and knew little about the XB-35 and YB-49.
This was the aircraft that led the way for the B-2.
Northrop Tacit Blue - Wikipedia, the free encyclopedia
BTW - although the Westland-Hill Pterodactyl flew before some of Northrop's flying wings (he was building any flying flying wings before WW2) I doubt the Pterodactyl any any influence on Northrop's XB-35 and YB-49 which were actually designed and constructed during the war years.