In some cases, weeds do good things for the yard and garden. Certain types of weed flowers attract friendly insects that remain to prey upon undesirable pests such as aphids, bean beetles, and whiteflies. Umbelliferous weeds (those with umbrella-like seedheads) such as Queen Anne's lace, host beneficial insects like lacewings. In Northern California, savvy homeowners allow some wild blackberries to grow near their gardens because of the many beneficial insects they host. Other weeds type plants, such as motherwort, a pretty Eastern weed, attract bees which aid and abet the essential pollination process among the plants in the landscape.
