A photo guest book - polaroid and washi tape! Get a cheap but cute polaroid camera, a blank notebook, and washi tape in your chosen colors. Have guests take photos and then leave a message underneath. Love this, but polaroid film is expensive and rare!
Spring Flower Garland - DIY - How to create an amazing floral decoration. (Use silk and dried flowers for garland that will have future uses: grapevine door wreath, mantel decor, table decorations, etc.