Gigi, my dad can't tell weeds from plants so I have to "supervise" him in the garden. But then again, I have weeds, I have plants, and then I have weeds that I want as plants. Since I'm a butterfly gardener a lot of those weeds are host plants for the caterpillars so I don't pull them. Many of them are seasonal and go away when it heats up. I think some look pretty nice, too. Virginia Pepper Grass can look quite good and it feeds the Checkered White and Great Southern White butterflies. And Spanish Needles are one of the best nectar sources there are. They are also a host plant for the Dainty Sulphur. Of course, you have to keep Spanish Needles under control because they will take over every sunny spot you have! But I let them go during the winter so the butterflies have enough to eat.
Right now I have a lot of Tassel Flower in the backyard. Both the reddish and lilac varieties, neither of which are native. And I have all these great nectar plants in my yard and I keep finding the butterflies on the Tassel Flower.
Don't they know I planted all that yummy stuff just for them? And they ignore me for weeds! Non-native weeds!