By the platform near Cupcake Junction tearoom (the former Tettenhall station on what is now the Smestow Valley Railway Walk) a group of mushrooms growing on dead wood. These are glistening inkcaps (Coprinellus micaceus). These look as if they have already attracted the attention of some slugs or snails.
The dead wood they are growing on can’t be seen: it’s probably dead tree roots. Lots of fungi grow on dead wood, and play a vital role in recycling its constituent elements.