So, one good thing to note. When it comes to eyes on animals (also known as amigarumi), they don't need to use safety eyes or anything like that, they can just create sewn eyes from black/white yarn and the like. There are a lot of really great amigurumi patterns/books about geeky/video game crochet as well, so those might be good for your son.
One skein wonders is a popular book, so that would be a good choice. Sea creatures also looks interesting. Crochet ever after will require too many bits to be worthwhile, but their other book, beastly crochet has more potential, but i don't see an amazon seller for it. Crochet animal hats is adorable and will do well.
As for other books you may want to look into:
The Big Book of Little Amigurumi
I have made patterns from some but not all of these, but if she's made stuffed animals before, she'll be able to follow all of these. And like I said, patterns calling for saftey eyes can be replaced by just hooking some yarn into the fabric instead. I hope these help!
Its from The Big Book of Little Amigurumi by Ana Paula Rimoli. You can get it on Amazon: https://www.amazon.com/dp/1604685816/ref=cm_sw_r_cp_awdb_t1_CoQ9DbFRDPT1G
I loosely followed this pattern from [this book](www.amazon.com/dp/1604685816/ref=cm_sw_r_sms_api_7ryuxbFTCCRA8) instead of the shell in the pattern I used the third hexagon pattern on this site It was a fun project!