Why does Helen collect reindeer moss as noted in the memoir, H is for Hawk?

Helen encounters reindeer moss early on in the book. She collects the moss because it reminds her of the lessons about patience her father taught her when she was a child. The moss is special because it can survive in any conditions. It patiently waits to get out of any dangerous conditions so it can recover and return to normal. The moss ends up reminding the character not only of patience, but also of her father.