Be sure to use the classic, A Tree Is Nice by Janice Udry. A simple but memorable craft is to make leaf-rubbings.
Ehlert, Lois. RED LEAF, YELLOW LEAF. Watch a maple tree grow from seed to sapling and watch the leaves change color.
Gove, Doris. MY MOTHER TALKS TO TREES. A girl joins her mother on a walk where she learns not to be embarrased when her mother talks to trees.
Houghton, Eric. THE CROOKED APPLE TREE. A favorite tree will be missed when a family moves.
Lionni, Leo. A BUSY YEAR. Mouse watches his friend the tree grow and lose its leaves throughout the years.
Maestro, Betsy. WHY DO LEAVES CHANGE COLOR? This easy nonfiction book describes how and why leaves change color.