Creating these paper lilies doesn't require a green thumb -- just the outline of a hand.
Have your child trace his hand onto a piece of white card stock (regular paper works too but isn't as durable) and cut out the shape. Cut two double leaves from green card stock and punch holes in the centers where the leaves meet, as shown.
Curl the paper fingers and leaves by wrapping them around a pencil.
Wrap the hand around the top of a green plastic straw and secure it with tape. Slide the leaves onto the straw and tape them in place. For the flower's stamen, fold half of a yellow pipe cleaner in half and curl down the ends. Insert the folded end in the straw.