I found such a large lichen on the floor, on the banks of the River Lune at Kirkby Lonsdale, which had probably dropped from the high canopy of the long established decideous trees. It is called Ramalina fraxinea. It was large at the size of about 8"x6". Here is a photo of the beauty.
Ramalina fraxinea - found on the side of the River Lune 12th January 2022