The idea behind 'sewing green' is to use organic and "repurposed" materials to make clothing, blankets, and purses.
I find the "felted foliage" scarf (made from old wool sweaters) endearingly funky. It's the one the gal on the cover of the book is modeling.
Another version of this leaf scarf:
This fashionista blogger walks you through the steps to make the colorful, wearable leaves.