No sentencing date was immediately set for Rivers, who entered her plea Monday in federal court in Beaumont. She faces up to one year in prison and a $100,000 fine.
Officials in late 2007 and early 2008 received complaints of missing or undelivered mail on a rural route. One customer said jewelry she ordered was not delivered.
A Feb. 29 search of the Rivers home turned up undelivered mail on a barbecue grill.
U.S. attorney's office spokeswoman Davylin Walston says Rivers, when questioned at a post office that same date, was wearing a ring identical to one reported as not received.
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