"someone" wrote

Neotiella rutilans (syn. Peziza rutilans) - saucer-shaped, up to 1.5 cm.
Scutellinia umbrarum; Scutellinia scutellata (Eyelash fungus); - these are
quite flat and around 1 cm in dia.
Sarcoscypha coccinia (Scarlet Elf Cup); Aleuria aurantia (Orange peel
fungus) - these are up to 5 and 10 cm dia, and cup-shaped, not flat.


Thanks to all

A number of relevant points raised!
Looking at the links above, it most closely resembles the Scutellinia in
form and size - although it appears even less fleshy than some of the pics.
Just like a flower petal laid on the ground.
There may be a wood connection, as there were some Blue Lawson Cyprus firs
in a nearby border until a few years ago.
They are predominantly on a clay border but have migrated into the adjacent
lawn.
Guess I'll just keep an eye on it and see how it progresses.

Phil