I was trying to remember the other E Nesbit book that I loved (something about a castle?)
This is it:
In this book, Jerry, Cathy and Jimmy meet Mabel, the housekeeper's neice who lives in the Enchanted Castle. With the help of the magic ring that Mabel finds in a hidden storeroom, they experience all kinds of magical adventures. This book is absolutely filled with magic of the most magical kind - statues coming to life, secret rooms filled with treasures and wishes come true. At the end of the book, the magic ring is traded in for a wedding ring.
There is a movie version of this too. :-)
This is the one Stephanie remembered reading as a kid. In this book, five siblings are having a holiday in the country when they find a Sand Fairy in the sand pit. The fairy must give them a wish every day. What will the children wish for? Whatever they ask for, it all seems to turn into a disaster, until their final wish not to have any more wishes.
"It's startling enough to have a Phoenix hatch in your house, but even more startling when it reveals you have a magic carpet on the floor. Conceited it may be, but the Phoenix is also good-hearted, and obligingly accompanies the children on their adventures through time and space -- which, magic being what it is, rarely turn out as they were meant." - from goodreads.com
If you pick up another E Nesbit book (maybe one for adults!), it would be wonderful if you could post a quick summary or review here. I would be curious to hear about her other books....