From Longman Dictionary of Contemporary Englishcloverclo‧ver /ˈkləʊvə $ ˈkloʊvər/ noun [uncountable] 1 
HBPa small plant, usually with three leaves on each stem. If you find one with four leaves, it is thought to bring you luck a four-leaf clover2 → in clover
HBPa small plant, usually with three leaves on each stem. If you find one with four leaves, it is thought to bring you luck a four-leaf clover2 → in cloverExamples from the Corpus
clover• At the moment it looks more like a bit of rough pasture ... full of dandelions and clover patches.• Domestic vines and orchards, in patches of garden overgrown with poppies and clover, straggle as far up as the fortress.• All permanent pasture and most leys contain a large number of grasses, clovers, weeds, and herbs.• It has a long creeping rhizome from which leaves similar to a four-leaf clover develop in two rows.• He took it out to hold and to watch it munch clover.• As befitted an earth sign, Taurus was made of clay, a sturdy little bull comically smelling a floret of clover.• Thoughtfully, Hera pulled a tuft of clover from the ground and offered it.• Can you taste the clover in it?Origin clover Old English clafre 