We all like to receive flowers every now and again — after all, it's encouraging to know that someone else is thinking of you. Tap into this goodwill by having a carnation day on Valentine's Day or Sweetest Day for your next fundraiser. It's one that works particularly well for schools.
Carnation flowers are relatively inexpensive to buy, and you should find you can get a decent deal on prices by buying them in bulk. Have a word with the nurseries, greenhouses and florists in your area and see if they'll be able to help you out with supplying the flowers.
The next step is to have pre-sales of the carnations before school and during lunchtimes in the week leading up to the big day. Put together cards that have space for the student's full name, their homeroom and a personal message. You'll need tables to sell the cards and pens on hand so that the students can fill them out. Keep collection boxes nearby to put the cards in (you might want to sort the boxes alphabetically or by homeroom to make them easier to sort). A cash box with small bills and coins for change will also prove useful.
When the morning of Carnation Day comes around, have some people grouping together the flowers with their cards, and other volunteers actually doing the deliveries. All of the recipients will love hearing their names read out and receiving the floral gifts. You might want to order in extra so that all of the teachers and the principal are covered as well.