Eventually, Isabella coughed up what looked like a hamburger pickle, but closer examination revealed it was two rusty metal rings stuck together.
"She pulled these things out of her mouth. She was like, 'Aw yuck'."
Ms Dally approached the restaurant manager to complain and was unimpressed by the response.
"They weren't very interested, they didn't really care for me, to be honest.
"I said, 'This is my 2-year-old daughter. It could have beenmuch worse - she could have choked'."
The manager took her details and said they would be in touch with the New Plymouth family but Ms Dally said no one contacted her.
After several frustrating calls to the Sylvia Park branch, on May 13 Ms Dally was called by McDonald's head office and told they were investigating and would be in touch.
But nearly a month later, she is still waiting to find out what caused the burger bungle.
"They didn't even offer to give my money back or to compensate my meal - not that I would want to eat there now - but they were pretty slack about it, really."
A McDonald's spokesman said it appeared the restaurant had followed the correct procedure, completing an incident report and bringing the foreign object to head office for investigation.
"McDonald's takes any food safety complaint very seriously. We have policies and processes in place to carry out a full investigation to establish how a foreign object may become present."
The investigation was ongoing.
"We contacted the customer to update them several weeks ago, and are awaiting further detail before we provide a formal response.
"We apologise to the customer for the delay in the process, but will provide them with a detailed summary of the investigation as soon as we can."
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