Many mothers have extra in their supply to where they could make an extra effort to pump a little to help out a baby in need or other mothers must pump for a variety of reasons and have a huge stash in their freezers. There are plenty of resources to donate this milk.
www.milkshare.com This has multiple states, choose your state.
Eats on Feets Facebook page https://www.facebook.com/EatsOnFeetsHome?ref=br_tf You can also choose your region to join.
Human Milk for Human Babies https://www.facebook.com/hm4hb Find your local chapter
I like these options because you often get to meet the mama and baby your milk is going to and you get to know exactly how your milk has helped each baby. It's a special relationship and I've actually made some very close lasting friendships this way.
So if you have some extra time to pump or extra milk to donate, then consider these organizations. And if you want a recommendation, I do know some babies in need at the present time. Please feel free to contact me also if you'd like to donate.