Soft Eggs and putting leaves and stick on her back?

[DigMyChicks]

I have no idea, but could that be nesting behaviour?  Chucking the leaves onto an (imaginary) nest?  What do chickens do in the wild?

I have one that does that and I think too she's building her nest...no soft eggs with her though.

 

[flocking-crazy]

I'm sure I've read about or seen this behaviour on video before and it's to do with nest building instinct, but normally it's done in the nesting box or at least in one place rather than wandering around doing it.
She looks healthy enough but the thin shells are a problem. I have a Blue hybrid that lays them and if I don't remove them as soon as they are laid, they get broken and eaten by the next bird that goes in to lay and I have sticky nest boxes and eggs to clean. This has been going on for over a year for me but as she is otherwise healthy and happy and laying eggs, I don't have the heart to cull her. .