According to the Massachusetts state lottery, Lundstedt didn't realize he won Monday's drawing until he stopped by the store to buy paper towels the next day.
The trio stopped by the lottery offices to pick up their prizes on July 11.
The Lundstedt children each received $100,000 before taxes. They both told Mass Cash they plan to use the money to pay off their student loans.
Lundstedt, a carpenter, took home about $700,000 before taxes.
He said he planned to use the money to pay off the mortgage on his home.