All kinds of things can be used, I like to buy evaporative cooler pads (the kind with the shredded aspen) and cut them up. They don't get kicked or tracked out of the nest box like shavings always do. I am using them now for my baby brooder poultry too, they provide better footing and I don't...
Interesting, I'll have to investigate those Seramas and where they come from, not familiar with the breed, must be a little something different in their background...
One of my barred cochin hens is stirring up the bedding in the hen house and making nest shaped areas... she is almost 5 months now, so maybe soon.... maybe I will put a nest box in there with her, she is in a grow out coop still.