The caps are grey when young, becoming white and translucent as they mature, and are very sticky and glutinous.   The gills and upper part of the stipe abve the thin membraneous ring are also white. 

Photograph from top down, in side view and from underneath to show gills and full length of stipe.  Note habitat and substrate.

Beech trees, on standing or fallen logs and branches, clusters are often seen high up in the beech canopy on dead branches. 

Autumn

Widespread but not really common in Britain

Occasional in Leicestershire and Rutland.

https://www.first-nature.com/fungi/oudemansiella-mucida.php