Buff-coloured tuft fungus.
Caution: Do NOT use iSpot to identify fungi to eat!
Some fungi are very poisonous so a mistaken ID could have serious consequences.
No interactions present.
You say growing in a grove of yews, but it is unclear if on soil or on wood.
If on soil, it might be Psathyrella multipedata (the clumps would be arising from a common base). [The dark brown spore print and white-edged gills agree.]
It was on soil about a foot from the base of a Yew; I thought it might be growing from wood just under the surface. Psathyrella multipedata seems to fit pretty well except that the books say it lives in open deciduous woods in summer to autumn, not dark Yew groves in winter. But this is an odd year. It was quite brittle and fell to pieces when I tried to cross-section it with a sharp knife, which might also be right for P. multipedata judging from the common name Clustered Brittlestem.
Lat/Lng: 51.410977, 0.097394
OS grid ref: TQ459700