I'm 46 and I'm not a sparkly-thing-in-hair wearer but I don't see anything wrong with them. I like the slightly goth-y with sparkly stuff look. Do you have fab shiny black bobbed hair? Some jet bead hair items would look good.
I wear hair flowers or a bandana with everything, but it goes with my style rather than just plonked on an unrelated outfit IYSWIM. I don't think you can be too old for them as long as you carry it with confidence Sparkles are not my thing though, I look like a mad five year old it's a shame as they can look fab on other people.
I'm 36, v petite and have a leaning towards quirky. I have blonde bobbed hair. Currently an asymmetric cut. As bobs can be a little dull I often wear oversized flower hair accessories. I stick to shades I like - teal, mustard, emerald or nude shades. I avoid sparkle.
If my hair is up I am never without a flower (I have about 10 different colours - usually oversized) in my hair. My hair is pinned up messily with either a quiff at the front or my fringe curly & down. The flower is clipped underneath the 'bun' to one side.
I love it ! I don't wear glitzy stuff though.
I'm 40 in a few weeks. Always feels like it finishes my 'look'