So I've found these mushrooms near a ditch on a field a few days ago in Romania. Can anyone help me with identifying what species of mushroom is this? The size of a mushroom is about 3-6 cm in diameter. Thanks and a happy new year.
This is most likely Kuehneromyces mutabilis or sheated woodtuft. It is quite common in Romania where it is named Gheba ciobanilor.
Quote from Wikipedia about the diagnosis:
The clustered shiny convex caps are 6–8 cm in diameter. They are very hygrophanous; in a damp state they are shiny and greasy with a deep orange-brown colour towards the rim; often there is a disc of lighter (less sodden) flesh in the middle. In a dry state they are cinnamon-coloured. The gills are initially light and later cinnamon brown, and are sometimes somewhat decurrent (running down the stem). The stipe is 8–10 cm long by about 0.5–1 cm in diameter with a ring which separates the bare, smooth light cinnamon upper part from the darker brown shaggily scaly lower part. This type of stem is sometimes described as "booted". This species always grows on wood, generally on stumps of broad-leaved trees (especially beech, birch and alder), and rarely on conifers. It is found from April to late October, and also in the remaining winter months where conditions are mild. It is often seen at times when there are few other fungi in evidence.