I finished reading The Wonderful Flight to the Mushroom Planet last night. This is a new paperback that, for some reason, doesn't have the wonderfully odd illustrations that the original has. It's less because of that, but the story stands well alone. I just wonder if A will be able to understand the allusions to a 1950s world enough to enjoy the story.
I've started reading the second book in the series, Stowaway to the Mushroom Planet. I bought that one some years ago on ebay, I think; it's an old library copy and has the illustrations by Robert Henneberger that I love so much. These are the only two that I found as a child, but there are three more in the series, all available online at http://www.abe.com/ (American Book Exchange), which is where I found a copy of my all-time favorite child's book, Mystery Island, about 15 years ago.
Mystery Island is the "American" version of The Island of Adventure by the prolific British author Enid Blyton. I don't know why they say it's "American" because I just couldn't tell the difference between the two when I found the entire series in paperback around the same time I bought Mystery Island at ABE. At that time I had to order the paperbacks from England; they weren't available in the US, as far as I could tell, but it was worth it. They're set in the 1940s, I think, and are really dated, much more than the Mushroom Planet books, but I guess the English (as from England) references and sayings contribute to that.
Now it's easy to find the books of my youth. Aren't the internets a wonderful thing?