Hi Gail,
My colleague does not consider herself an expert on lichen, but she wanted to direct you to a few resources
that may be more helpful: The Arnold Arboretum (http://arboretum.harvard.edu/) would be a good place to try
to ID them, also the Harvard University Herbarium in Cambridge (http://www.huh.harvard.edu/) and the
UMass Agricultural Experiment Station, which is now headquartered in Amherst
If she can't remove actual samples to bring along to show them without injuring the bark of the tree
(and it looks like she has 2-3 different kinds at least from what I can see in the photos) she'll want to
take some good close-up photos to bring. Also, knowing the types of trees they're growing on might help, too.
Attached here is an online key for identifying basic lichen types....she might want to give the ID a try herself!
I hope this helps you with your identification question.
Best, Maggie Rabidou