anyone know about 'charms' for book bags?

[nowwearefour]

My dd1 starts in reception in September. They all have to have these identical book bags which are stored spine up in a box in school. We were advised to get a unique 'charm' thing to put on our child's book bag handle. I dont really know what this is, where to buy it = i dont want to get it wrong and have my dd1 embarrassed because of my ineptitude! Anyone able to help me out at all?

We use key rings that ds has collected on holiday. Currently about 3 on his book bag. Means it stands out instantly as everyone else seems to have personalised their book bags with stickers. First day back at school today and ds was very pleased to see his Paddington Bear keyring on his book bag (bags kept at school over the summer!).