There is much more to figure out what is edible and what is not. Considering shrooms alone, it is much more "complicated", so much that there are specialists for that, even, but I agree, could be an useful skill, but not for people who do not even leave the city, I think.
However, they should know the basics such as "not eating potatoes (or its parts) that are green", and so forth, since that is something you run into even if you never leave the city. Food spoilage in general would be useful to teach, but that is the job of the parents, I would say. That said, my teachers in elementary school always used to tell me that they are our second parents. I can see where they were coming from.
I didn’t say there wasn’t. My point is that explaining to kids why they can pick a strawberry from the forest floor, but leave the fly agaric where it is, despite being the same color, is hard enough without going into the phylogenetic peculiarities.
Starting with animals (things that can think like you), plants (things that eat light), fungi (underground webs that bloom above ground), and bacteria (very small things that are sort-of alive, and can both be good for you or make you sick), makes things so much easier and is probably all you need to know for a while.
However, they should know the basics such as "not eating potatoes (or its parts) that are green", and so forth, since that is something you run into even if you never leave the city. Food spoilage in general would be useful to teach, but that is the job of the parents, I would say. That said, my teachers in elementary school always used to tell me that they are our second parents. I can see where they were coming from.