21 week white rock likes to gather eggs

[BCMominMD]

I have a large community nest box with 2 stone eggs in it. Not all my girls are laying. One of my EE's is laying a blue egg almost every day. The interesting thing is the white rock pullet will gather the stone eggs and ?her brown egg altogether in a little pile and sit on them for awhile. She uses her beak to tuck the pine shavings all around her. She sits for less then 30 minutes. Today the EE waited for her to get up and then ran in and layed her blue egg in the pile
Is this just normal hen behavior or do you think she will get broody?

 

[cmom]

I don't think it means broody. I have one golf ball in each nest box. Lately I have been finding multiple golf balls in one nest box. The mystery is how? Here is a picture of my nest boxes.

 

[BCMominMD]

Now that IS a mystery!!! How do they do that!!?

 

[AmyRey]

Can they hold an egg under their wings maybe?

I dunno. I'm stumped too.