The girls I mentioned above, who made these before me, made them from felt, and I did too, but I think you could be creative with what you have on hand. I think felt is such a great, wintry, warm choice. And guys, this is so easy! Just cut the templates (or make your own), trace, cut and glue together! I had some acrylic felt in the basement but while we were out the other day Dabney and I picked up a few 9x12" sheets of a few more colors for $0.29 each at JoAnns.
Dabney chose hot pink and baby blue. I think the baby blue ones sort of look like sweet little hydrangeas.
If you trace and cut carefully, you can make at least 3 flower pins per sheet of felt! Not counting the hot glue and the pin base (look for them in the jewelry making section) that's less than $0.10 per flower! Quick, cute and cheap~ my kind of craft.