Very cool! Legbars are actually know for their odd egg shape, I don't believe every single Legbar lays eggs like this, but many lay large eggs that are almost round! Mine layed very distinctive eggs compared to my Easter Eggers. I bet that's where she's getting that trait from. Legbars also very...
Since Leghorns lay white eggs and Legbars lay sky blue, if she's laying olive eggs, she has a brown egg layer in her lineage :) Very likely a Welsummer :) Pretty girl!
They're Eggers of some sort, look to have Cream Legbar in them at some point. I wouldn't be surprised if they were Olive Eggers. Regardless, they are not a purebred, just a designer mutt