Pagan bard Gwydion Pendderwen’s album Songs for the Old Religion (1973) was the first openly Pagan LP ever, that I know of. (There was Guitar Grimoire too, but it was all instrumental.)
On the Agora Patheos blog, Dana Corby tells the story of how it was made (part 1), including why they left in Gwydion’s mumbled remark, “Play louder, I can’t see.”
I learned just how little Gwydion understood about recording: they expected to complete an entire album, without prior rehearsal, over a 4-day weekend. He’d never even sung into a microphone before and had to be taught how to modulate his voice instead of bellow and to strum his guitar rather than whack it for all it’s worth like you do to be heard across a campfire.
With recordings of some of the songs.