Here are my favorite tools for learning about nature with your child. Start with outdoor time, good shoes, and a sketchbook. Children are natural explorers.
A nature explorer needs a good magnifying glass (with a soft bag or other holder so it won't get scratched easily) and a way to ID plants, insects, and animals. You can get apps for your phone, but I suggest Pocket Naturalist Guides by Waterford Press. These guides to trees, birds, mushrooms, mammals, and more are a must have. Unlike guide books (which I also like) these cards are laminated and take up very little space. They are easy to carry along and even very young children are able to identify plants and animals from the illustrations.
For a magnifying glass any good one will do. It should magnify at least 3times (3X). You can find them online. I am including a link here for a Montessori source because they also have other useful items for children exploring the great outdoors or the local park. Happy exploring!
The Pocket Naturalist Guides are from Waterford Press...