This month's plant is often used as a symbol for luck. There are actually scores of species and they are very diverse. In the month of March these BUDs are sold as shamrocks in honor of some human holiday which recognizes some Irish dude who drove the snakes from that island. Anyway, some people call these shamrocks clovers and some call them oxalis. Some call them sorrels and some call them mediks.
Truth is - they are all right.
The plants, although they are of a different species, and even a different genus, look very much alike. The most common clovers have white flowers and are often called weeds when they invade a lawn. They attract bees when they bloom. Oxalis has yellow flowers. It is considered lucky to find a shamrock with four leaflets instead of the usual three.