"Buttercup" is a song written and performed by American singer-songwriter Lucinda Williams.

The song features Elvis Costello on guitar and Matthew Sweet on backing vocals.

Her pride beams with moments of 'I told you so', but her empathic nature forces, her to consider the brokenness behind the subject's wrongdoings.

"[2] AllMusic wrote "Buttercup" is "a rollicking kiss-off to a former boyfriend in which Williams simply lays out the truth as she sees it amid a strident rock & roll cadence.

The guitars swell and fade while the B-3 swirls around her voice and the low-end drums hammer her vocal accents home.