She invited them over for a 'special meal'. The mushrooms she served allegedly killed three of them.

Almost two years after it's alleged Erin Patterson fed poisoned beef wellingtons to her estranged husband's family, a trial is underway in a small regional town.

Amid intense interest in the case, dozens of documentary-makers, journalists, podcast creators and true crime novelists have descended on Morwell, Gippsland, about 150km southeast of Melbourne.

Fifteen jurors — 10 men and five women — were selected on Tuesday, with 12 of them to decide Patterson's fate through a unanimous verdict at the end of the trial.

Patterson is accused of serving a poisoned lunch to guests at her Leongatha home on July 29, 2023, Justice Christopher Beale told the jury before the selection began.

Her husband, Simon Patterson, did not attend the lunch, but his parents, Don and Gail Patterson, and his aunt and uncle, Heather and Ian Wilkinson, did attend, he said.

Her former in-laws and Ms Wilkinson died in hospital after the lunch.

It's alleged the meal was laced with deadly death cap mushrooms. This is everything we know about the case and the trial.

Erin Patterson wanted a 'special meal' for lunch.

Patterson told her estranged husband she wanted to make a "special meal" for his family before she allegedly fed them the death cap mushroom-laced beef Wellingtons, a jury has been told.

The prosecution has begun to outline their case against Patterson, 50, who faces a six-week trial at Latrobe Valley Law Courts in Morwell, 155km southeast of Melbourne.

She has pleaded not guilty to three charges of murder and one of attempted murder over the lunch at her Leongatha home in July 2023.

Crown prosecutor Nanette Rogers SC opened her case on Wednesday when she revealed Patterson wanted to hold the lunch to seek advice on telling her children about medical issues.

Patterson invited all of the guests to the meal, along with her estranged husband Simon, at a Sunday service at Korumburra Baptist Church, where Ian was the pastor, Dr Rogers told the jury.

Don and Gail Patterson were the parents of Patterson's estranged husband. Image: Supplied.

The day before, on July 28, Simon sent a text to Patterson declining her lunch invitation, because he felt "uncomfortable", but was happy to talk about Patterson's health another time, she said.

Dr Rogers said Patterson, in her reply to Simon, "emphasised the effort she put into the lunch and said she wanted it to be a special meal and she may not be able to have a lunch like this for some time".

Patterson organised for her children to be out of the house for the lunch on July 29.

After her former in-laws and Heather and Ian Wilkinson arrived at her home, Patterson served up individual beef wellingtons consisting of a piece of steak covered with mushrooms and wrapped in pastry, Dr Rogers said.

She served wellingtons with mashed potato and greens and gave her guests four large grey dinner plates, while she ate her meal off a different small tan-coloured plate, the jury was told.

"They said grace and started the meal, Ian and Heather ate an entire portion, Gail had half a serve and Don ate hers and his," Dr Rogers said.

"There was banter amongst them about how much they'd eaten."

Heather and Ian Wilkinson. Image: Supplied.

After the main meal, the group tucked into a dessert of cake and a fruit platter, brought by Gail and Heather.

Patterson then revealed to the group she had cancer and asked their advice about telling her children. They told her it was best to tell them.

"They prayed for the accused's health and wisdom," Dr Rogers said.

Patterson's barrister Colin Mandy SC will give a reply on behalf of the defence on Wednesday afternoon.

Justice Christopher Beale told the jury witnesses will include Simon Patterson and Ian Wilkinson, as well as a number of medical experts, doctors and police.

Three attempted murder charges brought against Patterson regarding her husband have been dropped by prosecutors, Justice Beale told the jury on Tuesday.

The trial continues.

More to come.

Feature Image: AAP.