How many clovers need to search for finding a single one with four leaves? The ratio is about 1:10.000, so perhaps the only act of luck here is to find one.
When someone finds these clovers, it's nice but statistically it would be rare the same luck at the same field the next day, so... it's an assumption: it doesn't provide luck if the same person cannot find another the next day.
It would be a measurable percentage of luck if the person constantly defeats the ratio while others are still finding one between thousands. The term luck itself is a rather complex one, sometimes including metaphysical beliefs of an object modifying the structure of the Universe, because tiny or not, this is what it implies.
How it be, clovers don't have luck. For sure it's nicer when you have an entire organism.