Brachyscome spathulata is occasionally white. The number of petals and the number of bracts durrounding the base of the flower head fit that species. However, if the leaves belong to the daisy, they are iffy. Were there leaves on the flower stalk? If they were, I would have to rethink the ID. I would have expected Brachyscome diverifolia here, which has leaves up the stems. The leaves you have photographed do not fir it, either.
A photo of at least part of the stalk will help. And a photo of a whole plant. I think you may have to put a bag eg foot cut off a stocking, over the flower once it starts to fade, and wait till the seed matures so you can collect it. That is the gold standard for Brachyscome IDs.