four-leaf clover 四叶草；四叶苜蓿
 

【例句】
Four-leaf clover having four leaflets, considered to be an omen of good luck.
四叶草有四片叶子，被认为是好运的预兆。
 

Out of curiosity, I asked the owner of the four-leaf clover is how so many come.
出于好奇，我问店主这么多的四叶草是如何得来的。