This is one interesting topic, I should say. I never know that this kind of leaf brings luck to its finder. Although I've seen images of this around and it's often associated to leprechauns and Saint Patrick's Day, it never came to my curiosity why this mythical creature always has this. I thought it was just all part of the design. Also, I have little to no background of Saint Patrick, therefore I did lots of googling for this.
About the Four-Leaf Clover
Here is one useful information provided by Wikipedia.Org.
The four-leaf clover is a very rare variation of the common three-leaf clover. According to traditional sayings, such clovers bring good luck, though it is not clear when or how this idea began. The earliest mention of "Fower-leafed or purple grasse" is from 1640 and simply says that it was kept in gardens because it was "good for the purples in children or others". A description from 1869 says that four-leaf clovers were "gathered at night-time during the full moon by sorceresses, who mixed it with vervain (also known as verbena, Verbena officinalis, and herb of the cross, is a perennial herb native to Europe and Asia - www.healthline.com) and other ingredients, while young girls in search of a token of perfect happiness made quest of the plant by day". The first reference to luck might be from an 11-year-old girl, who wrote in an 1877 letter to St. Nicholas Magazine, "Did the fairies ever whisper in your ear, that a four-leaf clover brought good luck to the finder?"
Four-leaf clovers have been associated through common folklore with good luck and fortune. The probability of its occurrence if extremely low thus having found one is pure luck already. In addition, it is said that four-leaf clovers are always carried by Leprechauns other than the sacks of gold which they usually hide at the end of the rainbow.
About Saint Patrick
I found this informative article at History.Com which briefly explains the history of Saint Patrick.
Saint Patrick, who lived during the fifth century, is the patron saint of Ireland and its national apostle. Born in Roman Britain, he was kidnapped and brought to Ireland as a slave at the age of 16. He later escaped, but returned to Ireland and was credited with bringing Christianity to its people.
Why is Four-leaf Clover Used in St. Patrick's Day?
For those who doesn't know would certainly ask the same. It was actually because St. Patrick used the three-leaf Irish clover to explain the Holy Trinity (Father, Son and Holy Spirit). This three-leaf clover, native in Ireland is also called Shamrock. In many places, this terms "clover" and "shamrock" are being used interchangeably which is incorrect. Sporcle.Com noted some differences and exhaustively tackled important points of information about these two.
Difference Between Shamrocks and Clovers
Clover, also known as a trefoil, is the common name for various species of plants in the Trifolium family. It is estimated that there are around 300 different species of clovers found throughout much of the world (Sporcle.Com). It can be easily be distinguished with its alternate compound leaves which usually have three small leaflets. Shamrock on the other hand, is a Gaelic word meaning “little clover”. It's one of the many kinds of clovers and is traditionally used as a symbol of Ireland. Generally, a three-leaf clover can be considered a shamrock. Otherwise, it's just a clover.
Now that I learned this information about a four-leaf clover and why it is associated with luck, I will now proceed to respond the prompt. Actually, I had seen plants similar to clovers in our place. They were considered stray or wild plants and aren't planted on one's flower garden. I'm not sure if they are clovers or not but it perfectly resembles to it and are very similar to the images of clovers I found while doing my research.
We also have our own version of luck finding. Instead of a four-leaf clover, ours is a six-leaf dwarf santan
flower. Santan flowers are not only best for making garlands but also used when we want to wish for something. Normally, santan flower has only four little leaflets but if you're lucky then you'll find five or six. Until now I still found myself scanning over that blooming shrub along the pathway while going home from work.
Pretending that I found this magical clover, then here's my lucky day story:
Finally, I am on my way home after years of failed visit. Work has stalled my opportunity to go home. I only have one rest day and our home is far from the city I work at. I have to endure my longing to see my parents and siblings. But today, I got the chance after filing a week of leave from work. Although our way home is never pleasant as I have to walk through wet and muddy alley, the thought of seeing them prevails. With my ankles deep in mud, I squelched across a meadow. Just when I'm about to step on this bed of some three-leaf wild weeds, something caught my eye. A four-leaf one emerges and I'm surprised at how it differs from the rest of them. I bend for a closer look, pick the leaf, put it in pocket then wade my way home. I arrive and just when I'm about to knock, my phone rings. It is from an unknown caller cheerfully announce that I win from their online lottery I happened to participate few days ago. I am very much surprised that it brings me to jig with a sudden delightful scream. The door opens and I am surprised again when my brother (who currently stays in Manila) appeared. He only laugh and said "Surprise!". It's not fair. I wasn't told of his coming but I'm more than glad that we are complete now.
That was fun! I wish that it really happened. Thank you for reading this! Cheers!
Footnotes
http://www.stuartxchange.org/Santan.html