In keeping with the nature theme, our daughter dressed as a flower the year, our son dressed as an apple tree! To put together the flower costume, my mom made a tutu out of green tulle. She basically gathered the tulle and sewed it to some elastic (there are lots of tutorials online with various levels of difficulty, so I would recommend doing a search for more detailed instructions!)
Then, I used green RIT dye to color a white shirt and tights to match. We put a hot pink sash around her waist for extra cuteness! The petals were a lot more difficult to create and needed quite a bit of tweaking to get right. We cut petal shapes out of stiff hot pink felt (you may need to glue petals together to get them even more stiff and straight.) Then, we put a piece of wire through each petal and wired each one to a headband. Then we stapled them to each other and added some below her chin. We put some tape on the underside of the headband, so the twisted wire wouldn’t bother her head. We gave her some daisies to carry around too!
Our daughter got lots of compliments and her costume was definitely much cuter than the store bought ones! (In my opinion anyway!)