snoopy - have you read some of the history of Alfred Wallis? He never had a formal lesson and only took up painting very late in life.
there is another Cornish artist in the naive mode, Bryan Pearce. His paintings are rather controversial as he suffered a condition caused by a strong rejection of mothers milk - something that is now a basic test done in Agpars....it left him mentally disabled with an age of about 11-12, though he had adult knowledge of choral music and trains. When he was about 18, his aunt gave him a splash-on water paint book and he loved in and that was it, he was away....... It did help that he lived in Piazza in St Ives (alongside a rack of artists and others who had apartments there, such as Hepworth, Bernard Leach, Janet Leach (separate flats), Barnes-Wallis and writers such as Holliday. He was sponsored by Alan Bowness, who became the Director of the Tate and was Hepworth's son in law (maybe a case of, "not what you know, but who you know").
Anyway, his paintings are commanding some serious prices now.
My parents took him up on the cliff-tops near Zennor and set him up in a field. When they came back from a walk, he had painted the cows - with their udders on at the wrong end. I have a couple of his signed limited prints, but wishI had got an original when I had the chance - then about £250.
http://www.google.co....QsAQ&biw=1345&bih=562