I , too, find accents and dialects fascinating and my interest was even more fired when I did Bernard Shaw's "Pygmalion" for O level. I was brought up in Portsmouth, went to a school where received pronunciation was the norm and remember being mortified when a girl I was chatting up remarked that I "talked posh". Yet every day I heard the accents of the Navy around me. These were the days of National Service and lads from all over the country were brought together, Their own locally acquired accents were soon overlaid with a common Naval accent and I could tell the difference between, say, a geordie lad on holiday and a geordie sailor.
I used to have to sometimes remind my teaching staff that there are differences between accents, dialects and the written form of English. Too often, poor or even incorrect English is passed off as "accent". Written English has no accent and far less variation in grammar. Vocabulary may vary, however. For example, I have never heard Toddy speak so i have no idea whether or not I could understand what she is saying with my poor hearing. I do understand the written form of her posts despite clear differences in vocabulary. although I sometimes have to think hard about the meaning!
Anyone really interested in following up the points made in this thread should look up Bernstein's speech codes. He argues that children often use three languages; the one they use amongst themselves, the one they use at home and the one they use with their teachers. And he is not talking about foreign, but mother-tongue language. This is important in Education, because a middle class, southern English child raised in a home with parents speaking received pronunciation English has only one code to learn and is at an advantage as this is the dialect predominant in education and the media. A child brought up in a home where another dialect or language is used has effectively to learn a new language when they start school and may suffer delay. Mary-Jane Drummond, one of my old tutors used to point out that all children entering early years education have to do this anyway: "What does lead on from the front mean? "she would ask secondary school teachers.
I'm following my younger granddaughter's progress with interest. Now four, she lives in Spain with a father who has a southern/received English accent like me and a mother with a Mancunian twang to her standard English. She speaks Andalusian Spanish with neighbours and friends. Lucky girl!