Can anyone identify this/these please?

[Thomk]

My initial guess is leatherjacket egg cases

I fear you have a photo of Green Vegetable Bug egg cases there and it is very possible that the OP has a photo of them too. Crane Fly eggs look very different I think.

 

[Cress1968]

I'm no expert but that looks like a 20 pence piece to me.

Brilliant

 

[longers]

Do they smell mushroomey?

I didn't sniff them, but should have.
I also think they're too big to be Shield Bug eggs.

 

[laurence]

Grass snake eggs? Probably too small... could have been dropped by a bird after eating whatever was inside.
There's a CCer who is an expert on snakes, can't remember his CC name.

grass snake eggs are pretty small, but probably not that small. too early for grassy eggs too. snake eggs are leathey and tend to just collapse once they hatch.