Looks like what they call a corrugated/wrinkled shell or body checked egg http://www.thepoultrysite.com/publications/1/egg-quality-handbook/18/misshapen-eggs http://www.alltech.com/sites/default/files/alltech-egg-shell-quality-poster.pdf
Poster from Alltech (Corrugated Eggs on the left middle row) and The Poultry Sites page for those.
It says they are from damage to the egg while in the shell gland from various causes, or an inability to control "plumping", (the step in making an egg, when it goes into the shell gland, the egg spends a couple of hours absorbing water and salt through the membranes, before the shell starts to form).
If it is just one bird doing it, it is probably a problem specific to that bird (shell gland), not sure if there is really anything that you can do about it besides make sure she is on a proper diet and not being stressed if you can.
I just got one yesterday from an EE so was interested to see the picture of yours, they sure are funny looking.
Thanks. Yes, she is a tad stressed and hen pecked by the "alpha hen".We had them separated for a few weeks and she went through a spell of not laying... go figure!