For your beginning reader, Little Critter: The Fall Festival is a great book, with big lettering and easy to sound out words along with descriptive pictures, all with the childhood favorite Little Critter and his family celebrating the harvest season.
The Little Yellow Leaf is another good one for early readers to read along with their grown-ups. The illustrations are great artisitically, and might inspire some craft ideas - in addition the story is a great tale about friendship and taking leaps of faith.
For the more scientific and curious child What Happens in Fall? by Sara L. Latta, from the series I Like the Seasons! does a great job of explaining what causes the leaves to change colors and fall, why the weather gets cooler, the days shorter, and how animals prepare for the coming winter.
Translated from Japanese, Hooray for Fall! tells the story of three little squirrels discovering the beauty of autumn's colors.
Last but not least - We're Going on a Leaf Hunt takes the classic children's chanting game "Going on a Bear Hunt" and gives it a fall twist. The children in the story hunt for the leaves of different trees squish-squashing their way through the woods - and it is their adventure that is the inspiration for today's activity: Leaf Collage!
Go out on a nature walk in a nearby park or forrested area with a well-marked trail. On the way observe the animals gathering nuts and berries for the winter and take some time to gather your art supplies. Pine needles, grasses and especially the fallen leaves of a variety of trees all make good choices for your collages. You may need to dry and flatten your leaves before you can use them for your craft project by putting them between sheets of paper towel and laying a heavy book or two on top for about half an hour. Then use crayons, markers, colored pencils, water color etc. to draw your scene if you wish. Or you can do an abstract collection. Whatever you choose, white school glue or glue dots work the best for sticking your collected flora to your paper. Most importantly, have fun, be creative and take some time to enjoy Mother Nature!