The teenage son of Patterson has described the relationship between his estranged parents before a death-cap mushroom-laced lunch.

He told the police that the relationship was "very negative" in the months before she served a deadly beef Wellington lunch.

Patterson's 14-year-old son described his parents' relationship in a recorded police interview played to the Victorian Supreme Court on Friday in his mother's triple-murder trial.

Patterson's son told police his mother moved houses about seven years before the deadly lunch after having a "couple of arguments" with his father, Simon Patterson, although the couple did not divorce.

The original arrangement was for the children to stay with Erin during the week and Simon on the weekends, but that changed in the year before the lunch, the boy told police.

"I know dad does a lot of things to try and hurt mum, like messing around with the school," he said in his interview.

"Mum didn't put his name on the billing for the school ... but dad wouldn't talk to mum about that. He would just ring the school and tell them to put his name on the billing."

The boy told police he had been living solely at his mother's house in the past year, even though Simon was trying to convince him otherwise.

"I didn't want to," the teen said.

"He never did anything with us over the weekends when I did stay there."

The boy said his mother felt sick the day after lunch, so they did not go to church, but she still wanted to take him to his flying lesson, more than an hour's drive away.

The teen told police his mother did not need to pull over to use the bathroom during the drive there and back, although she rushed to the bathroom when they returned home.

The jury was told Patterson served her children the leftover steak, potatoes and beans from the lunch for their dinner on the Sunday night.

The jury was told that while the boy did not love mushrooms because they were "squishy and mushy", he believed his mother did.

He recounted a time in mid-2020 when he and his mother found some wild mushrooms growing in the Korumburra Botanic Park.

"I remember mum took a picture of them because she thought they looked nice," the boy told police.

"It was just a very fond memory."

They did not pick the mushrooms, and the boy said he had never been foraging for wild mushrooms with his mother.

The trial before Justice Christopher Beale in the regional town of Morwell will return on Tuesday.

With AAP.