Wet Log Liverworts and Mosses
One of the best place to find a reliable assemblage of bryophytes is the common damp rotting log along the forest floor. If you are trying the learn basic features and common species, said substrate is a good place to start. All around the decaying bark and wood are a set of microhabitats that dependably host a reliable assortment of mosses and liverworts. The following is a non-exhaustive list of bryophytes common to log microhabitats in the PNW. Each species is linked to "research grade" observations of these taxa in the inaturalist system so you can get a sense of what you are looking for. (l) is liverwort, (m) is moss, t is upright, ~ is prostrate and * connotes asexual reproductive bodies are common.
If you like habitat guides to bryophytes, I cannot recommend @david1945wagner 's guide to Important Bryophyte Habitats of Western Oregon -- broadly applicable to the regions between Northern California up to Coastal Alaska.
Over all exposed surfaces
Hypnum circinale (m)~
Pseudoisothecium stoloniferum (m)~
Scapania bolanderi (l)~
Rhizomnium glabrescens (m)t
Kindbergia oregana (m)~
Plagiothecium undulatum (m)~
Bazzania denudata (l) (very wet forests)~
Smooth, exposed wood
Lophocolea bidentata (l)~
Scapania umbrosa (l)~
Decaying wood
Cephalozia bicuspitata (l)~
Calypogeia mulleriana (l)~ *
Fuscocephaloziopsis connivens (l)~
Lepidozia reptans (l)~
In deeply shaded regions
Tetraphis pellucida (m) t *
Pseudotaxiphyllum elegans (m)~ *
On cut log ends
Riccardia latifrons (l)~
Cephalozia bicuspitata (l)~
