... and still made a top level career for themselves?
Tough question, because it all depends on your definition of professional.
Tony Book is the sort of answer you might be looking for...playing for Bath City, Malcolm Allison allegedly found him up a ladder, doing his day job, when aged about 29 he went to Man City, and captained them to the title and FA Cup.
We took Tony Gough, trying to follow the same template....it didn't work, quite so well.