It's weird that someone so prolific should be so (relatively speaking) obscure. You can't say that about Edgar Cayce.
It's fair to say that Cayce (you say "Casey"), who died in 1947, is still one of the most famous celebrity psychics, ever. Every single book I have about mysterious powers, predictions, or the mystic Atlantis mentions him. The History Channel did a (predictably sensationalist) documentary on him. He got a write-up in Prediction, obviously. You can find all sorts of writing about Cayce on the internet, adoring and sceptical alike, and there's a good selection of stuff at his own Association for Research and Enlightenment, the group he set up that's still going strong.
In summary, though, Cayce would enter a sleeplike trance, and then, guided by a questioner, present remedies, or reveal the past and the future of people who visited him or who had written to him in phrases that sound like, well, someone talking in their sleep. Seriously, it's really hard going, a stream of images and ideas, all jumbled up, with occasional lucid patches rising out of it here and there like flotsam bobbing up from under the surface of the sea. Thankfully, his stenographer Gladys Davies wrote it all down and a fluid group of other assistants (among them his sons Hugh Lynn Cayce and Edgar Evans Cayce, who himself only passed away a couple of years ago, in his high nineties) would edit and interpret what Edgar was saying. Edgar's readings became an industry.
I don't think that's wrong. Cayce used his talent to gain celebrity and, after a long period in the wilderness, supported his family with it. He won the right to do what he did in a court of law, sort of (sometimes court records are boring. This is really not. Note though that nothing Cayce says in the trance in question is even remotely right). I don't for one second think he was deliberately fooling anyone.
Now. On the one hand, Cayce's "readings," especially his assessment of what people wanted and his predictions of the future are widely praised for their apparent accuracy. I'm not going to go into that, although I expect you know where I stand, because he did thousands of readings. On the other hand, an awful lot of the people he "read" seemed to have past lives in Atlantis... which to be honest, sort of scuppers at least one layer of accuracy.
Cayce, for all of his Atlantean past-life regression, was, it turns out, deeply religious and read the Bible daily (as in, he picked it up and read the words, not, you know, did psychic stuff with it, although he claimed he could memorise a book by sleeping with it under his pillow), and it shows in the Atlantis readings, the cream of which are presented in a digest form with copious notes in Edgar Cayce on Atlantis, by Edgar Evans Cayce and Hugh Lynn Cayce, (New York 1968).
Atlantis was Eden. The two factions who factored in the Atlantean downfall were The Law of One and the The Sons of Belial. God was present, everywhere.
But those two factions are the same factions who feature in Leadbeater and Scott-Elliot, under different names, and while Edgar Cayce on Atlantis's bibliography features old standards Ignatius Donnelly and Lewis Spence (no Atlantological library is complete without them because without whom etc.) Scott-Elliot, to whom Cayce's "readings" owe a hell of a lot, is entirely absent. How could someone interested in past lives in Atlantis in the first half of the twentieth century have read Spence and Donnelly but not Scott-Elliot? It is not easy to credit, particularly when you see how similar Cayce's readings are to Scott-Elliot's account.
Cayce's inspirational sleeptalk builds on Scott-Elliot's over and over again. Scott-Elliot and Steiner talk about how man originally was dual-sexed; Cayce ties that in with the esoteric Adam and Eve myths (it's particularly redolent of the myth of Lilith). Scott-Elliot has the airships. Cayce has airships and submarines. Scott-Elliot's Atlantis has destructive weapons of colossal power, using unknown forces; Cayce's Atlantis has what his son interprets post facto as atomic power. Casey's Atlantis also has TV and computers. It's like Cayce's the diesel-age fantasy to Scott-Elliot's steam age one.
Cayce's Atlantis also has "Things". Leadbeater talks about genetically engineered half-animal slaves; Cayce makes them a massive cause of controversy among the people of Atlantis. He describes them as either animals elevated to a subhuman state, or people reduced to it, or both (I use both in my own fiction). They are living automata, he says. But would he have had this without Leadbeater? Maybe. It's a staple of science fiction as much as occult writing. The writing exists. Awfully similar, though, isn't it?
But, inevitably, race came up. Cayce himself said that Atlantis had five races (red, black, yellow, white, brown), and they arose separately and awakened to consciousness separately. his son Edgar Jr compounds that in Edgar Cayce on Atlantis by citing the work done after Cayce Sr's death by Carleton Coon, who was an anthropologist who wrote that humanity was five separate species and who also - although Cayce Jr didn't know this - secretly used his work to support Segregation (check out this absolutely fantastic and freely available academic article on Coon, academic ethics and segregation by John P. Jackson, of the University of Colorado. If you are at all interested in the history of racism in science, you need to read it).
I mean, again, the racism here isn't even intentional. Cayce Sr picked up racist ideas from his dad (and maybe Scott-Elliot). Cayce Jr read a story in a newspaper about a distinguished anthropologist and thought, quite reasonably, "This guy's a professor of anthropology! He must know what he's talking about."
Which confirmed basic unexamined racism. It's disappointing more than anything.
Cayce said Atlantis would come back. That Atlantean death rays and other artefacts would be found.
There's been no sign.
I can't blame myself for feeling disappointed about this too.