Piper at the Gates of Dawn
A lot of people think that stuff like The White Album was the cream of the crop of Psychadelia, but the Beatles just made mainstream friendly psychadelia. If you wan't the real stuff you have to listen to stuff like Piper at the Gates of Dawn.
Syd Barret is literally out of his mind, and give some of the greatest acidly crazy space rock ever produced. Astronomy Domine, Lucifer Sam, Pow R Toc H, and Take Up Thy Stethescope and Walk will send you into your happy place. And thats before Bike comes along and drives you insane with its doubled up vocals.
This isn't your father's Pink Floyd... it was too weird for him.