Luck of the horseshoe:  

Throughout Europe and the United States, Horseshoes are often seen nailed to barns and houses and as charms on jewelry. They are an accepted sign of good luck, though most people don't think about why that is. The origin is believed to be tied to the proscribed magical powers of iron. Iron is considered lucky because it is born from the marriage of rock and fire, two of the basic elements in ancient times. Blacksmiths, makers and users of iron, were alchemical masters of the elements and their byproducts. Accordingly, their creations were believed to be endowed with supernatural powers. These powers helped in a story that says the 10th Century Archbishop of Canterbury foiled Satan when he was disguised as a horse because of the power of the positive power of the horseshoe. The fact that well made horseshoes aided in the health of a valuable resource, the horse, also helped. In addition, the basic shape of the horseshoe, which is either a cup, a crescent, or an arch depending on your point of view, is traditionally said to be lucky. The crescent is a moon symbol that has luck-giving properties in ancient Mediterranean cultures because of moon-goddesses. Also, the typical number of seven nail holes in a real horseshoe is considered lucky in European tradition. All this added up to a strong belief in the lucky properties of horseshoes and horseshoes found should always be kept and nailed to the door of your house or barn. Probably relating to the allusion to a cup, horseshoes with the open end up are said to gather luck in the U.K. and Ireland (and the US, typically). However, many believe that the horseshoe itself is lucky and must point down to pour its luck onto you. More recent associations with horse racing and the gambling traditions of horse racing (wealth through luck) have added to the history of the lucky horse shoe. A very different origin story is that the Roman legions were the first to use horseshoes. The power of the legions and the sparks thrown off by the meeting of horseshoes and rocks created an association of horseshoe and power.

Luck of a Four Leaf Clover:

In Celtic cultures, particularly in Ireland, clover has long been considered lucky. The rare four-leaf clover is viewed as particularly powerful. Today both Shamrocks (three-leaf clovers) in Ireland and four-leaf clovers in the US and Europe are seen as powerful good luck charms.  The belief in the luck-carrying properties of clover probably began in Wales and spread to other Celtic cultures, including Ireland. It's origins are lost to time, but it is believed to have been a favorite forage of domesticated animals like cattle, horses, and sheep. Because animals well-fed on clover grew fat and made their owner wealthy, the plant took on the power to do good things for people. The four-leaf variety was especially valued because of its rarity. Others think the four-leaf clover had added power because the druids used clover in spells and believed the leaves represented the four elements of alchemy (Water, Earth, Air, and Fire) and/or the four seasons of the year. The introducers of Catholicism to Ireland co-opted the belief in three-leaf clover (the Shamrock) by saying this represented the trinity of God, son, and holy spirit. The rare four-leaf clover added a leaf for God's grace. Even in recent times, carriers of the four-leaved clover were believed to have been granted special powers to see fairies, detect witches and recognize evil spirits. Clover was also said to protect cows from witches. Unmarried female travelers were also advised to place clover in their right shoe to meet the man they were to marry. In France. The four-leaf clover is a rare find in a patch of nutritious and luck-bearing clover. Its rarity is thought to give the four-leaf clover enhanced luck-bearing properties which may be able to help you!