I can't see whether there's a ring or collar beneath the caps - doesn't look like it, so its probably a harmless toadstool - its there because you've got dead wood in the ground, it's part of the rotting process. Remove the dead wood and the toadstools will disappear.

I think it might be worth digging down into the soil to see if there are the distinctive black bootlaces and white mycelium of the honey fungus down there. Although there are no collars/rings visible in the photos the rings on the honey fungus sit quite high up and the clumped growth and colour is more or less right.....

If it's honey fungus then that is not good news as it can spread across the garden and it is death to trees.....

A photo of the underside of the caps would be useful. And also look for the remains of a white ring or collar at the top of the stem.

It does look like honey fungus. but there are 7 different species and not all have bootlaces nor are all rampant bringers of death and doom. [according to what the RHS told me] My garden has had an outbreak, one of the ones that doesnt have bootlaces and only invades dieing tissue anyway.

I would bag the toadstools and dispose of them in the bin, to prevent any more spores being released .

That's interesting Seaburngirl because that isn't how the RHS website reads: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=180

I come at fungi from the mushroom side rather than the gardening one and I hadn't realised there are members of the group that lack the bootlaces.....

My RHS Pest and Disease book does say there are several different types of Honey Fungus, and some are more virulent than others. Certainly when we had it in a garden I look after 2 years ago, I found not one single black mycelium 'bootlace' anywhere at all, yet the fungus had been slowly killing woody plants in that area for the previous 3 years before we realised what the problem was - on the appearance of the toadstools with rings.
The question here is whether the fungus in the picture is honey fungus - if it doesn't have the ring or collar, I'd say not, but its hard to be 100% about that. If its honey fungus, was that what killed the Photinia originally? Or has the current crop of toadstools arrived because the dead remains of the Photinia are present in the ground.... Either way, it would be much better to remove all trace of the dead wood from the ground.

Thank you to Bamboo, Cestina & Seaburngirl. I shall be out there with a spade to see if I can find anything else, below ground.