However, after an elaborate treasure hunt, which took more than an hour, with 20 adults and children all dressed in their pirate best, it ended with no treasure.
Someone else had got there first.
"When we got there, the treasure was gone, there were a lot of sad pirates," she said.
Mrs Walker made a Facebook group plea with the public to return her son's treasure.
"I was really gutted, because I had planned this for three years. I'll admit I did cry," she said.
Four months later, while camping, Mrs Walker received a text from her husband saying the police had found her treasure.
"We were all saying it was a Christmas miracle," said Mrs Walker, with a laugh.
The chest was so realistic that when a Good Samaritan stumbled upon it they thought it was lost property and took it to the police.
Sergeant Drew Allison, of Wanganui, who was in charge of the case, was dedicated to discovering where the chest came from.
The chest, bought by Mrs Walker at a second-hand store, had "L. Ward" inscribed on the top.
"I spoke with the [Whanganui Regional] museum and Alexander Library to find where the chest came from, which led on to inquiries with relatives of Lillian Ward, who by chance were Mrs Walker's neighbours," said Mr Allison.
"The neighbours remembered we had a treasure hunt and the treasure went missing," said Mrs Walker.
Mr Allison applauds the man who handed the chest in to police, saying: "I'm happy it got back to the people."
It is still unknown if Lillian Ward was the first owner of the chest.
Mrs Walker says she will try to re-do the treasure hunt for her daughter Sophie's fourth birthday party, hopefully with better results.
