When I worked at a lesson barn the girls loved grooming totes. They could show off to their friend's while useful and also nice to know what's yours- and have something that's yours instead of something from the barn!
Like this: http://www.doversaddlery.com/horsewa...te/p/X1-10162/
They're available in all sorts. Get a nice one (some are cheap and the tools are horrid). Also make sure the barn allows this, some barns each horse has their own brushes to prevent germs and such (though they might make an exception if her brushes are only being used on one horse).
Mostly the younger girls were into that. If she shows a nice appropriate (and you WILL need to do your research on appropriate for show gear!!!) item is great. A girl got a very nice quality smart black crop- with her initials monogrammed on it. Sweet simple and very stylish.
Treats are always good: http://www.doversaddlery.com/german-...b/p/x1-220203/
Not the ultimate gift to HER of course but cute to throw in ALWAYS. Again check on barn rules.
The jacket idea is really
nice but I know I am picky myself. I ran with the Dover suggestion above but they really are great to work with and top quality, one of my top pics. SmartPak is another good site though designed a little differently.... Horse.com is cheap and has a lot of variety. Hmm... LOTS of options!! How nice a gift are you looking to get? A little awkward to phrase it that way but I'm sure you know what I mean. If going for casual barn gear in general is ALWAYS good. Boots, mittens, thermals, anything horse themed. Honestly even a lesson package or opportunity like a clinic that you signed her up for would be nice even if indirect. If she's serious getting in with a big name clinician (if even an option) would be pretty huge. It's all so dependent.
Careful with the car ideas, here you don't drive on your own until 17 at the earliest and definitely no guarantee of your own car then either!
A boot/helmet bag or something is always nice.... check if she needs any actual equipment.
It's super nice that you came on here just to research! There are soo many options and a lot of it depends on how the barn works and how she is involved unfortunately.
Some other nice gifts were monogrammed pads and even -for a few girls that rode the same horse usually-their own halters. A lot of it is having something nice that is yours that other people don't even have lol. Plus, as barn staff, it helps out the barn staff to know what's what! lol