Instructions
Use the left analog stick to move your cursor onto the Garden Store.
Press "X" on the Xbox 360 controller to view the contents of the Garden Store.
Use the left analog stick to highlight the item you wish to remove.
Press the "A" button on your Xbox 360 controller to remove the item. You are automatically taken out of the Garden Store and your cursor is holding the item you selected, allowing you to use it in your garden.