My informant and her brother have a book in which they taped four leaf clovers they found in the front yard and taped them into a little notebook. When I asked why they did this, they said that their mom told them that it would give them good luck. When they heard it, they ran out the door and tried hunting for four leaf clovers. I was surprised when I discovered that they actually managed to fill two pages and I checked the book itself to confirm that they were actually four leaf clovers. My informant said that after she collected the clovers, nothing happened to them, so she and her brother stopped believing in the four leaf clover. When I asked her mom about where she got the idea, she said that she and her sister used to look for four leaf clovers while they grew up in New Jersey. But they never could find any, so she thought maybe her kids could look for them. She joked that just finding the clovers might have used up all the luck.
From this, I understand that the four leaf clover superstition comes about from the rarity of the item, which means that when you find one you can feel like you can get the luck. However, when someone actually does come across such an item, or in this instance many, the faith in such an object dwindles. That small joke their mom cracked actually shows how even though the results aren’t showing, the beliefs are still strong but neutered a little. A similar story occurs here (http://www.jstor.org/stable/1497230), which shows how people still stubbornly hold onto beliefs despite seeming to deny it after the results have given nothing.