The Jackson Citizen Patriot reported it was the first day of school for the boys, who are 5 and 6 years old.
Blackman-Leoni Township Department of Public Safety official Jon Johnston said school administrators called police Friday afternoon when the 44-year-old woman showed up. She fled on foot before officers arrived.
The boys live with their mother and father a few blocks from the school. Johnston said they were turned over to their father, and the Michigan Department of Human Services was contacted.
Police said the woman is on probation for a prescription fraud charge. Her probation officer and Jackson County Circuit Court have been notified.