text: Uses Early spring greens and buds of Caltha palustris are edible when cooked (but are poisonous when raw). Young leaves or buds should be submerged a few times in fresh boiling water until barely tender, cut into bite-sized pieces, lightly salted, and served with melted butter and vinegar. Very young flowerbuds have been prepared like capers and used as a spice.
  The common marsh marigold is planted as an ornamental throughout temperate regions in the world, and sometimes recommended for low maintenance wildlife gardens. The double-flowered cultivar 'Flore Pleno' has won the Royal Horticultural Society's Award of Garden Merit.
  Culture
  Caltha palustris is a plant commonly mentioned in literature, including Shakespeare:
  Winking Marybuds begin
  To open their golden eyes (Cymbeline, ii. 3).
  It also appears in Charlotte Brontë's Shirley:
  They both halted on the green brow of the Common: they looked down on the deep valley robed in May raiment; on varied meads, some pearled with daisies, and some golden with king-cups: to-day all this young verdure smiled clear in sunlight; transparent emerald and amber gleams played over it
  and in Thomas Hardy's poem 'Overlooking the River Stour':
  Closed were the kingcups; and the mead/Dripped in monotonous green,/Though the day's morning sheen/Had shown it golden and honeybee'd.
  Kingcup Cottage by Racey Helps is a children's book which features the plant.