Important disclaimer! First and foremost, I am not a lawyer, nor am I an 'expert' in copyright or legal matters regarding copyright. The information I'm providing below is information I've learned to be true from information shared by copyright lawyers in the United States, which is where this information is pertinent. I know your location is listed as Texas so you should basically be covered, but if you are reading this and asking questions about copyright for your country, it is absolutely best to do your own research and check for the differences as there will be some.
There are a number of factors that come into consideration here. First is the issue of copyright. This is a very simple breakdown and it's not all encompassing, but I think it will answer your questions. If you take a photo and you are not doing so as a requirement of your employment, you own the copyright to the image (ex: the Boston Marathon bombing police sgt that took photos as part of his job - he did not own the copyright to the images he leaked to the press because he took them as part of his job duties) You have the right to share them and use them for almost all purposes, with the exception that even you cannot use them in a commercial setting without a model release if there is an identifiable person in the image. Obviously there are other rules/regulations, but this is the simplest way to describe this situation (I feel). One other thing to remember though is that for any claims for copyright, you have to have to submit the images in order to copyright them, so that's the first thing you would want to do. This is a relatively simple process and can be done digitally but it isn't free (but it's relatively cheap, $35 I believe for electronic submission).
Just giving copies to your friend (was she a client? Did she pay you? Did you have any sort of contract) does not necessarily grant her any particular rights, but by not having a contract, all the friend would need to say is that you had a verbal contract (which may not stand up). It could simply be that your friend posted the images to Facebook or something, and someone from the league saw the image, and used it.
In absolute terms of black and white, you technically could request that the league take down the image to which you hold copyright as they are technically using the image without permission. If you were to ask them to take down the image, and they failed to, you could request a DMCA take down via their ISP. Obviously, this is drastic and should be avoided, because word gets around quick with parents that feel they've been 'wronged', and the last thing you want is a bad rap (or worse).
The question is, what do you have to gain from doing so (or from their using your image without permission)? It's pretty much a no-win situation. Asking them to take it down is basically going to make you look like a bad guy, but if you feel strongly about the image being used, what you may want to do is get in touch with who's in charge of the website and make a comment along the lines of 'hey, I noticed you used this shot for your website. I'd be happy to provide more images for you if you'd like, but in the future it would really be best if we had an agreement so that you could continue to use the images and protect all involved parties in the long run.' Make them feel like you're doing it to protect them as well, but try to do so without making it sound like you'll go after them if they keep using your images.
Also, there isn't much to be had in terms of value if you go after them. You would need to basically demonstrate financial loss (meaning you'd have to demonstrate that you have sold images or rights to images in the past) in order to get any sort of meaningful monetary value out of a suit, and suing for any sort of damages definitely requires a copyright on file (within a certain number of days of the image being available in the public domain for maximum value). The exception to this rule is the watermark removal rule, as editing an image to remove a watermark specifically for the purpose of reusing the image is actually a big no-no (and fines can get pretty quick per instance).
There, clear as mud.
Edited by MistaBernie - 4/23/14 at 10:09am