You get the buttons at guest relations when you redeem your voucher. You only get a button when you redeem a voucher so if you only redeem one voucher that day, you only get one button. Here are photos of the buttons:
Do you think there is any chance they would give my DD (4) a button? She voluntered with us, but obviously isn't able to get a voucher. I would hate for her to feel left out. Of course, I will give her my button if they won't. . .
Disney is great about things like that -- so there's a good chance...if not there's a generic celebrating green button she could wear or you could wear and give her yours...you can write in what you are celebrating, like "I'm celebrating Giving a Day"