I think this is Common Rustgill - Gymnopilus penetrans. 3cm across the cap and 4cm tall, rust brown spore print. Found in conifer plantation growing on rotting wood.
These were growing on the side of the path through a field. Largest one about 15mm across growing flat to the ground. I thought possibly Melastiza sp. but there doesn't appear to be a hairy margin.
Any help gratefully received. JohnB