Some traditional good luck charms include the shamrock, horseshoe, rabbit's foot, penny and rainbow. Additionally, some other traditional good luck charms are wishbones, acorns and goldfish.
In Irish tradition, shamrocks have four leaves; one leaf is for faith, the second is for hope, the third is for love, and the fourth is for luck. Similarly, the Irish consider a rainbow lucky because of the alleged pot of gold at the end.
The rabbit's foot seems to have gained its lucky connotation because of the rabbit's association with spring, fertility and rebirth. A rabbit's back foot is purportedly luckier than its front foot because its stride causes its back feet to touch the ground first.