Looks like an Easter Egger! What a wonderful chickie! Are the legs bluish or greenish? I can't tell from the pics. If so, definitely an EE! Yea!!! Green or blue eggshellsssssss!!!
I got my order from MMH also and I have a chick that looked exactly like yours when was little... now she looks like this:
I'm trying to find out what breed she is as well. Someone suggested she was an araucana (the easter egger). I ordered 2 araucanas but any other pullet looks like her!!
I also have another "sui generis" looking chicken, which I think is the "free rare" one: