Mary says she is 11 on the 1860 census but no Mary or Polly Breeding shows on the 1850 census for this family. She is also last on this list of children in 1860 below George W. who is 8. This could mean she is out of order or it could mean Mary belonged to a different Breeding family and was staying with or being raised by Alexander and Mary - but if so who?
Image Gallery
1860 Census Soap Creek, Davis, Iowa - households of Alexander Breeding, Casper Mohler & wife Mary A. (Breeding) and James Livingston & wife Sophia (Breeding)
References
1860 U.S. Federal Census.
Soap Creek, Davis, Iowa, United States (with parents)