The expectant parents dropped by the Two and a Half Men star's hometown of Cedar Rapids, where they spent quality time with relatives and enjoyed a Sunday brunch at Granite City Food & Beverage.
An eyewitness tells E! News that the two came in with Ashton's younger siblings and his twin brother.
"Whenever Ashton is home he comes into the restaurant, but people generally leave him alone," the source added.
Both Mila and Ashton "seemed very happy and relaxed."
Mila ordered an egg white omelet and sipped on both a coffee and orange juice during the morning meal.
The future husband and wife were seen making their way through an Iowa airport on Saturday afternoon.