To the many people who have been identifying unknown lichens as genus Lichen: it has recently been brought to my attention that the genus Lichen has not been in use for some time and is synonymous with Parmelia (details), so I'm retiring it. In the future you should identify any unknown lichens as kingdom Fungi. I know that's not very specific, but lichens as a group do not conform to any one taxon: they do not all share a common ancestor because lichenization (probably) evolved numerous times. It's sort of like trying to identify a tall, woody plant as a "tree": linguistically accurate, but not taxonomically meaningful. Some day we might develop non-taxonomic categorization schemes for iNat, but until we do, identifying unknown lichens as Fungi is the way to go.
That being said, a quick search on Index Fungorum reveals numerous species in the genus Lichen that are considered synonyms of species outside of genus Parmelia, so in favor of extreme taxonomic conservatism and to correct all the misidentified Lichen observations, I'm just swapping Lichen into Fungi.