The 82-year-old Dunedin resident has twice been diagnosed with breast cancer and underwent a mastectomy earlier this year.
The society’s annual Daffodil Day fundraiser took place yesterday and about 1500 Otago and Southland volunteers were out selling the yellow blooms yesterday with the goal of raising $500,000.
Mrs Walls said she supported Daffodil House, a place for out-of-town cancer patients to stay while receiving treatment.
It was a cause she had been supporting for years, as the support of the society had been "invaluable" .
She did not think she could have got through without them, as having cancer was a big mental adjustment, in which people began to think about their life expectancy.
Her first breast cancer diagnosis came after a scan 13 years ago.
It was the last year she was entitled to a free mammogram, available for those aged 45 to 69 under the programme BreastScreen Aotearoa.

"I just had a lumpectomy the first time, this time I’ve had to have a mastectomy."
The second diagnosis came as a shock, but she believed the tumour had now been successfully removed.
"I just have to be careful because they weren’t too sure whether they had left some cells on the chest wall, but they’re going to monitor that."
The society ran different support groups, and she attended both the coffee group and the craft group.
"It’s like one big family, you get to know everybody.
"Everybody’s cancer is different, but you’re all needing the same support."
It was a difficult time for some people, and they appreciated a friendly face and a place to air their worries, she said