Can anyone tell me where I can purchase any of Ray Bradbury's earlier works containing Joe Mugniani illustrations?

Well, let's see, from the top of my head this could include:

THE GOLDEN APPLES OF THE SUN - has interior illustrations. Most editions up until the mid-90s had the illustrations, but recent printings have sometimes left them out.

THE HALLOWEEN TREE - the first edition has them, but I'm not familiar enough with later editions to be certain whether they are in there.

There's another book that has them, but I forget which one it is (and I can't get to my notes to check at the moment). I'm sure somebody else will come forward.

My advice would be to get onto Abebooks.com, because the listings on there usually carry specifics about which edition is up for sale. I would recommend either first edition hardcovers, or early edition hardcovers.

You might also find Jerry Weist's book RAY BRADBURY: AN ILLUSTRATED LIFE useful, since it has dozens of Mugnaini illos, and some useful publishing info about some of the editions. It's not flawless, but pretty good.

Ron, simply go to the website of the Advanced Book Exchange, type in "Ray Bradbury" in the "Author" box, and then type in the word "Mugnaini" in the "Keywords" box (make sure you spell his name correctly, as it is misspelled in your post). You will end up with a list of hundreds of Ray's books with illustrations by Joe Mugnaini. Depending on whether you are looking for an inexpensive reading copy, or a hard cover first edition in dust jacket, there are a wide range of books and prices to choose from. Here is a link to the Advanced Book Exchange website:

www.abebooks.com