Each of these images are plant parts that hold new life inside.
Pine cones contain seeds, each can become
new pine tree.

This is a leaf bud, which contains a
new leaf and flower which will emerge in the spring.

This is a sweet gum pod which contains seeds, each seed can become a
new sweet gum tree.

This is a locust pod which has seeds inside, each seed can grow into a
new locust tree.