The Green and Burning Tree: On the Writing and Enjoyment of Children's Books, by Eleanor Cameron
Eleanor Cameron was the author of The Wonderful Flight to the Mushroom Planet and other Mr. Bass stories, as well as some other books too. This is a collection of essays and speeches from the mid 1960s about children's literature--writing it, reading it, and enjoying it. She talks about a lot of my favorites and mentions a few I think I would like to read.
At time she gets a little too misty-eyed about myth and children and all, but mostly it's some quite good stuff if you're interested in children's literature. I especially liked the last two essays, which were about Wanda Gag and Eleanor Farjeon. They were fun. But the whole thing was quite worth reading.