This is a game that girls play to determine whether or not a boy they like will like them back. The only reason I know about it is because my sister showed it to me. What you do it pick a flower, pluck off one petal and say, "He loves me" while thinking about the boy you have a crush on. Pluck off the next petal and say, "He loves me not". Continue until all of the petals have been exhausted. The loves/loves-not statement you made with the last petal is the one which will come true.
I cannot stress how important it is to pick flowers with an odd number of petals.
Cheat for expert play: if you find yourself on a "He loves me not" with the last petal, you can snatch a victory by throwing away the head and stem for a final "He loves me!"