I let some milkweed grow around my yard, though I seldom see butterflies using it. I let a big Bull Thistle grow by the front porch. Hummingbirds and bees worked the flowers. American Goldfinches first ate the aphids off the stems, then fed on the seeds and used some of the fluff from the seed heads for their nesting material. I wasn't so fond of Bull Thistle as a kid on a dairy farm as the pasture had a lot of it, but we also had lots of goldfinches.