Do you know what happened this morning at 7:30?

The female brought in what looked like a chunk of lichen, then flew off, then returned and seemed to try to feed it to the chicks?  Perhaps it was not lichen-like but something else. Then she covered then with her wings. I am watching form Portland Oregon and appreciate being able to ask this question.   I have read that they sometimes eat some lichen-like material, but this is the first time .