Animal Crossing: New Horizons\u00a0loves to celebrate its seasonal events, and the latest one available for players is Nature Day. It's all about being eco-friendly, right alongside the real-world event of Earth Day. During this event, you can earn additional Nook Miles for participating in specific Nature Day activities. One of these activities is to plant three Cosmos flowers. For those who don't naturally have the Cosmos flower on your island, there's no need to panic. You can easily obtain this item by speaking to Leif, one of the newest merchants you speak to who visits your island. He shows up on the first day of the Nature Day event right outside of your Resident Services center. He has a stall available, ready to sell you a variety of different shrubs and rare flower seeds from his inventory. You will likely find the Cosmos seeds available in his inventory. You can purchase them for a small sum, and then add them to your island. You need to plant at least three to complete this achievement, and when you do you'll be able to earn five times the amount of Nook Miles for your daily Nature Day activity, much more than you traditionally would with any of the standard actions you can complete daily to earn more Nook Miles. After planting all three of these plants of any color on your island, you're good to go. You should try to have a variety of them on your island to try and create hybrid plants of this variety, adding even more color to your island.