The Lucy in the Sky With Diamonds idea is a very popular misconception. It is NOT about LSD, actually. One of the Beatle's (I forget which) son drew a picture of some lady with a lot of jewelry and bright twinkly things around her. When asked by his father what the picture was of, he said it was Lucy in the sky with diamonds.
And now you know...the rest of the story. Good day!
aulharvey
EDIT: the unknown Beatle was Paul, by the way. I just asked my dad.