The white eggs will be coming from the Leghorns, which most of them look to be. That "plumper" looking girl may be a white Rock. If you have one that's not as slender as the other, I'd bet she's laying the brown eggs. White eggs don't turn brown ;)
Your rescue ladies are looking fantastic, by...
Aww, bless your heart! I would have taken them the first time :D
I went into TSC yesterday for feed and shavings and couldn't help myself, I had to look in the chick bins. They had 6 of the cutest little bantams left that nobody wanted. They employee working in the chick area said they'd sell...