Clover

Ah, a Clover from Terraria! Actually, it's purely a decorative item with no special functions or crafting recipes. It's a lucky find, but since it has no use, just enjoy it as decoration, hoou.

Apologies for the late reply, but the Clover increases your LUCK stat when held. Putting it into the Shimmer (iridescent liquid) will cause it to wither and have the opposite effect. There's no particular meaning to holding multiple. Simply put, the LUCK stat affects actions where luck is literally involved. (e.g., obtaining rare items, encountering rare monsters…) To be blunt, it's fastest to refer to the Wiki for detailed information.