Which of these is usually considered a symbol of good luck?

The four-leaf clover has always been associated with good luck and magical properties capable of attracting good energies and removing the bad ones from our environment. Keep in mind that it is a very rare species and, therefore, when someone finds it, they think it is by fate and consider it a good luck charm. It's so rare that there's only a one in 10,000 chance of finding a four-leaf clover in the wild.

Source: Marca.com