Autumn Woods are a biome added by ExtrabiomesXL.
Mostly flat terrain with some mountains of varying height, exclusive brown, orange, purple and yellow trees of small and large sizes. Climate is the same as that of Minecraft's forest. Mushrooms and wolves are scattered about. This is the main reason you like this mod.
Ground Cover: Grass
Trees: Oak, Purple Autumn, Brown Autumn, Orange Autumn, Yellow Autumn
Plants: Grass, Rose, Dandelion, Toad Stool, Autumn Shrub, Mushrooms
Fauna: Cow, Sheep, Chicken