Anastasia, Absolutely

Irrepressible Anastasia is in junior high now and participating in the "Values" curriculum through which students learn to make moral decisions. Early one morning she hits the Cambridge streets with her pooper-scooper to walk her new dog. In her half-awake groggy state Anastasia mixes up the two plastic bags she's carrying: one containing letters to be deposited in the mailbox for her mother and the other with her responsible morning gatherings.
She's too embarrassed to call the post office to confess and she begins to feel more and more guilty and scared as she notices some intense local police activity in the vicinity of the mailbox. What will Anastasia do?