I've had a minor life long interest in trees. When I was quite young, I came across my father's boy scout handbook. It covered at least 3 times more stuff than mine did when I later joined scouts. There was a very long section on tree ID. It went on for pages and pages, lots of leaf and shape silhouettes. This was followed by a section on making things w. specific woods.
We have always taken lots of walks. We had 4 kids, and one of the cheapest ways to entertain them was to go to a park, or camping. I did some foraging, and I would point out things they could eat, and those they should not. In the fall, we would always go out looking for pawpaws, and beech nuts. Side note. Pawpaws, sometimes called "Indiana bananas", produce absolutely delicious fruit that comes ripe, and then spoils in about 2 days. Get 'm while you can. Beech nuts have the highest oil content of any No.Am. nut. In the days when whale oil was most desirable for lighting, beech oil was second. Beech nut shells are so soft they can be peeled by hand. They are the first nut to ripen in the fall, and because of the tenderness and high food value, wildlife will eat them almost as soon as they fall to the ground.
Besides that, I have a very good resource. My wife and I joined a nature preserve/garden center. Just about every kind of plant on the property is labeled. So I get to stroll thru a 3-d botany catalog dozens of times a year. Eventually, some of the info rubs off.