It's funny you say that, I actually work at Michael's! I spend lots of time in the yarn section when I'm on my break! All of the yarn that I've used so far has been the red heart super saver acrylic. It's great yarn for beginners. The closest thing we have the yarn I'm looking for is roving wool but it just doesn't have the same look as the yarn pictured in the book.
I will flip through the book and see if I can't find anymore information on the types of yarns she used and see if I have any luck with that.
I kind of knew that this was going to be a fruitless quest but it was worth a shot!