Certainly Omphalina s.l. - but I think it might be possible to go one step better here. The ground around the stem bases is largely in shadow but there seems to be a good, green algal mat around the bases of these mushrooms - and (along with the yellow mushroom colour) that's very suggestive of Lichenomphalia chromacea (the algal mat being the photosynthesizing partner in this lichen). Do you recall there being an algal mat - or is this just my imagination?