Small weed flowers can feed adult beneficial insects. If they're not competing with your plants, leave small patched of weeds. Fungus can also create interesting shapes and colors in your woodland garden. I do not mean fungus that harms your plants. That type must be controlled to protect your garden.
Weeds can also pull nutrients from the soil.
Pick your weeds and compost them. You'll have a steady supply of nutrients from the deep dark depths of your soil. Eat your weeds. I don't personally do this, but lots of other people do. And when you think about it, most herbs are tough growing, poor soil loving weed-type plants.