You can tell this is a kids book because fairy is spelt 'fairy' as opposed to 'faerie' (though the picture on the cover and the fact that Enid Blyton wrote the book are also dead giveaways). I have noticed though that when you are dealing with children's literature it is fairy as opposed to fae (which is the plural of faerie and a word of Celtic origin).
The original fae were not nice people, and in many cases they were demonic. In fact Raymond E Feist wrote a book called Faerie Tale which dealt with the darker side of the fae, and also we see the darker side of this world in Shakespeare's Midsummer Night's Dream. In both stories the fae are scheming and manipulative creatures, though the Shakespearian creatures tend to be on the nicer side (though I would hardly call Oberon a paragon of morality). These were not the small and beautiful creatures that flittered around the bottom of the garden on gossimar wings, and were lovers of nature and teachers of morality to children.
However, this is what the fairies are in this book. The stories collected here jump between fables and aetiological myths. For instance, there is the story of how a toadstool became to be called a toadstool (there was a competition as to who could make the best gift for the fairy king and a toad came up with a one legged stool, so it became known as a toadstool), and also how wallflowers came to be called wallflowers (they grew on a wall).
However there are some morality tales in this book as well, probably to scare children into being good when they are read to at bedtime (don't tell lies because if you tell lies the fairies will take you to a land where nobody will believe a word you tell them, unless of course you are lying then they will believe you). Mind you, these are not bad stories, and for children, teaching them such things when they are children no doubt will help them grow up to be better adults (and is probably a lot better than having them play Call of Duty day in and day out, where the only way to solve problems is to run around killing people).
This is probably one of Blyton's earlier works (I noticed it dated as being written in the early 1920s, though I suspect that this was when many of the stories were written as opposed to when this compilation came about). They were probably written after the stories she wrote the books on the Greek and Roman legends, namely because it seems that they are following the aetiological pattern that came out of many of the Ovidian stories that she wrote in 'Tales of Long Ago'.