buttercup
n.a common yellow flower with a soft, round center that you can pop. It is often found in grassy fields and is popular in children's gardens.
n.a common wildflower of the genus Ranunculus, typically characterized by bright yellow petals and a soft, spongy center. Often used in informal contexts to refer to the plant or its flowers.
“The children picked a buttercup from the field.”
“We spent the afternoon picking buttercups and daisies to make a bouquet for the kitchen table.”
“While the buttercup is often dismissed as a common weed, it serves as a vital nectar source for early-season pollinators in the spring.”
“It sits beside a yard overgrown with stinging nettle and creeping buttercup, but its former status as an entrance of sorts is still clear.”
From butter + cup. Both sense 1 and 2 are from the flowers' association with butter, from their yellow colour. Compare butterflower for a similar derivation; outside of English, compare Dutch boterbloem, German Butterblume.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.