Ziploc bags, Sharpie, painter's tape
Go on a nature walk with your preschooler. While on your walk, collect leaves, stones, flowers, and bark. Let your child pick up different objects that represent the nature in your area. Put one of each nature item in a quart-size ziploc bag and seal. Label each bag with a Sharpie (e.g. "Yellow flower"). Tape the bottom side of all 4 bags together with colored painters tape. Now you have a book where you and your child can read and "open" or unzip the pages. Not only will you build your child's vocabulary and reading skills, but you can also learn about all the different trees and flowers in your neighborhood.