Here it is, in three versions:
My original, in prismacolor marker:

My second prismacolor version:

Finally, I worked one up in colored pencils, but thought that just pencil was too bland, so I outlined in ink:

I like the basic concept, and I think I like the markers better than the colored pencils. Not sure, ultimately, which paper I'll use (I used smooth marker paper for numbers 2 & 3; the colors are brighter and don't bleed - the not bleeding means they have a crisper edge, but large colored areas look splotchier; heavy drawing paper for #1, which has more texture and is not bright white).
Any thoughts about which one of these three you like best? Or which elements of any of them you think look best? Funnily enough, I think now that I've done three that my favorite is the first one, but I'd love to hear other opinions. :)
Oh . . . and in the time it took me to do maybe half of ONE of those drawings, Connor completed an entire garden alphabet of his own, and some of the illustrated letters are amazingly cute (IMO, anyway). Look at "E" for example - how sweet is that?

Since he didn't label his animals and plants like I did, this seems perfect for holding a contest. See if you can name the subject of each of his letters (you might want to click on the photo to see a larger version at Flickr), and the person (or people, in case of a tie) who gets the most correct will win a piece of original art by Connor (plus something extra from me; not sure what, yet, but I'll think of something nice). He said he'll draw whatever the winner requests. Sound like fun? Sounds like fun to me. :) So, start guessing! Oh, and I'd better screen comments until after the contest is over, so people who come along later can't just build on previous lists.
ETA: We've just noticed that "L" is missing, so don't worry about that one. Also I'm not expecting anyone to get Connor's "X" - it's not actually a real thing; it's something fictional from outer space (from a very obscure film). If anyone DOES get it, you'll get a Connor drawing just for that. :D
ETA2: We now have a tie in the contest. Both
ETA3: We have a new front-runner . . . Nicola, LJ visitor, book lover and homeschooling mom, guessed a whopping 18 correctly!
BTW, I plan to keep the contest open until Tuesday, or possibly Wednesday, to make sure that anyone who is away for the holiday weekend has a chance to play. :)