Nicky Holloway spotted the unsmoked cigarette at the bottom of a box of food her one-year-old was happily tucking into. I went straight back to the restaurant and demanded to speak to the manager, the 21-year-old said.
She claimed she heard the girl who had served her yell to a colleague: Leave me a fag, before she picked up her son Jacks French fries, cheeseburger and plastic toy.
I saw the girl but, when I told her what happened, she just laughed. To me it wasnt funny. I was so angry they werent taking me seriously, said Miss Holloway, of Southampton.
My son can feed himself and I was watching him eat but he could easily have put the cigarette in his mouth. Miss Holloway said the manager of the McDonalds branch in her home city offered her another meal or a £1.99 refund.
But she insisted on keeping the meal and toy from the childrens movie How To Train Your Dragon and contacted the McDonalds head office.
A spokesman for the fast food chain said a member of staff had made a foolish mistake. He apologised and offered to make amends with a gift and some free meals for the family.
But the deal was rejected by Ms Holloway, who also turned down an offer by trading standards officers to investigate the incident. She wants more to be done about it and plans to sue McDonalds.