Kaleidoscope (UK) come to mind.

Any others?

The Bee Gees, but admittedly their “psych” output is pretty limited. A few songs done by other artists like “I’ll Know What to Do” (Ronnie Burns) and songs from 1st.

Status Quo didn’t do drugs in their psych days.

The hollies as a group didn't, but Nash was a partaker, didn't they come out with a quote like we're as psychedelic as having a pint down the pub? Or something on those lines?

Genesis in their early days at least weren't partakers.

Frank Zappa

Wurzels?

Wurzels were rampant on this stuff plus scrumpy cider. Apparently Phil's sheds were major distribution points.

https://en.wikipedia.org/wiki/Mangelwurzel

Beware the evils of mangelwurzel!

https://youtu.be/y-iGEvnYsng

"Wurzels were rampant on this stuff plus scrumpy cider. Apparently Phil's sheds were major distribution points."


HaHa! Good one, Whoppo

And the assumption is they were being honest when they said they didn't take drugs? Room Of Percussion is very likely written about a bad drug experience and stands out on their debut LP as the only 'real' lyrics on there.

There would be lots of reasons for people saying they didn't do drugs at the time when they did.