These chickens were part of a Brown Egg Layer Assortment hatched around July 5th (6. months old now). I got 4 buff orpingtons, 1 buff rock (I think, she feathered in WAY faster than the orps and has yellow legs), 3 australorps, 1 jersey giant, and 6 white rocks. Most, if not all of them are laying.
If you bought them from Meyer, all your buffs are Orpingtons, they don't have buff Rocks. I love my buff Orps from them, they are such nice birds and so fluffy. I'm getting a few Australorps this spring, they lay so well and I love that shiny black color.
I was about to say the same thing. (Well, except I don't have any buff Orps or Australorps.)
Is it possible that she's a red sexlink / Golden Buff or possibly a New Hampshire? They both have yellow legs and I have seen some that are similar in coloration to Buff Orpingtons. One thing that can help determine if she's a sexlink or not is to look at her down by pushing her feathers up. Sexlinks have white down, while Buff Orps and New Hampshires will have down similar in coloration to the rest of the feather.