Bird and Animal experts?

Ok. So my mother wanted to cut down a tree in our backyard, so a family friend brought a chainsaw over and did it for us. They didn't realize that there was a nest in it until after it was cut down. within the branches and parts of the tree, we found the nest and two baby birds. One seems to be perfectly normal, but the other's neck is pretty twisted. My family friend's wife and I put them in a shoe box and took them to our area's nature center. Unfortunately, they told us that they don't take animals. They did give us a number of a lady to call for the bird with the twisted neck. I'm going to call that number, but I need some advice for right now. They told us to put the nest and the birds as close to the area where they were before and that the mother will come back. But some far, it hasn't and they both look starving. Is there anything I can do right now? They're babies, and can't even fly yet. Their feathers haven't even fully grown in. I'm not sure what kind they are, but they have brown eyes and grayish whitish feathers. They are about the size of those little apples that fit in the palm of your hand. If anyone knows anything I can feed them for now, it would be greatly appreciated.