I am not 100% sure this is an elm mushroom. The similarities are there, growing from a hole in the stem, several feet above ground. The colours are similar too and the size and shapes.
Growing on a dead tree stump
On scycamore
Miss Willmott’s Garden. Essex Wildlife Trust.
Rigid stem. Caps aprox. 2cm-10cm.
I'm thinking a Clitocybe. Maybe Clitocybe rivulosa