Farm Anatomy is pretty popular. I would check with Waldorf curriculum sites for other book suggestions. In Waldorf schools, kids that age do a unit on farming.
https://www.waldorfcurriculum.com/Class3/fg.html
If you’re OK with screens, there are a lot of good YouTube channels on farming… both for people on many acres and those in the middle of the big city. Look up “urban homestead” (this is what we did for several years before getting an acre!), especially the Dervaes Family.
Ultimately, though, this is something best learned by DOING than reading! 🙂
