What was the first album with psychedelic cover art?

[Johanna]

@mikecurtis

Not a direct answer to your question, but Vox links the psychedelic esthetic to Art Nouveau

I came here to say that. I think TV tropes would call that Older Than Television. I was going to peg it as Older Than Radio, but it turns out radio and Art Nouveau were both invented in 1890.