The mulch will help conserve soil moisture. Also, this kind of mulch decomposes over the winter and adds to the soil. Everyone recognizes crab grass and dandelions, but to learn what kind of weeds you are growing, check into Weed Images and Descriptions . It isn't too late to mulch and save yourself some frustration. Weeds are green, grow without planting, and provide a quick cover for soil left barren by construction projects, fire, etc.
Weeds are a foodsource for birds.
Weeds may actually produce some attractive fillers for dried winter bouquets.