To help you get ready for St. Patrick's Day, here is a set of Free Shamrock Clipart. I searched the net for this but decided to make my own because I prefer a puffier look to the shamrocks. I put together an assortment of green shades and white versions. All are png format, royalty free and can be used for personal or commercial use. So if you like, you can download your free copy here from my TpT Store.
I got the green background in my poster from Sassy Designs.