When I was a flower girl I believe I got earrings. My daughter will be our flower girl/ring bearer some how not sure how we are doing this as of yet. Ring Bearer if its sunny out a pair of sun glasses. I'm sure pintrest has some really good ideas.
For little wedding attendants you could give them something "grown up" that they could grow into, like cufflinks or a pocket watch for a boy, a pearl necklace or some other jewelry for a girl. However, what they would likely appreciate most at a young age is the sort of gift you'd get them on their birthday, like toys, games, or taking them out for a fun day! Gifts for the wedding party don't always have to be wedding related.