In the episode "Beaver and Violet" the Cleavers and the Rutherfords go on the picnic together. but where is Lumpy at. They don't even mention his name as if he doesn't even exist in there family!

I noticed that too. An interesting thing about the episode is that Mrs. Rutherford later became Nurse Chapel in "Star Trek," Deanna Troi's mother in "Star Trek: The Next Generation," and the computer voice in all "Star Trek" shows. Violet, played by Veronica Cartwright, became a well known actress, appearing in movies such as "Alien."