Most likely she is just fresh , try lunging her before riding .
Hello Kacy,
Does your horse live in a stable or outside. Because if she's living in a stable she may just need to go out more to lose her excess energy.
If she's living outside and still bucks, maybe you should lunge her a bit when you haven't rode her for a little while.
Good luck!
It's just freshness and excitement, shes not being naughty or mean