I've been looking for stuff like this myself. I've found a lot that are about psychedelics, but I've been having a hard time finding any that mention them directly. As for some good songs ABOUT psychedelics, basically anything by Tool. (If you get high and listen to "Intermission" off the Anemia album it's amazingly trippy. Make sure you do it in a dark room with headphones though, speakers won't work. You have to be able to isolate the tones in either ear.) Like Mrvitorsky said a lot of Pink Floyd involves psychedelic themes and if I'm not mistaken, even a few direct references. ("The Wall" anyone? Seriously, if you don't know it check out the album cover.) And most people don't know this, but "Drops of Jupiter" by Train is also all about a trip. If you actually read/listen to the lyrics closely, you'll notice all the references.
That's all I can think of right off the top of my head. There tends to be more songs ABOUT psychedelics, than there are songs that involve them. If I can think of anything more though, I'll be sure to post them up.
