Its been growing in a small bush in my garden without any watering, and it just flowered. The leaves look similar to feverfew or chamomile, but they are different, the chamomile or feverfew seems to have leaves which are wider, this plants leaves are like thinner and longer. Could it be an oxeye daisy or another kind of daisy? Any ideas?
I was initially going to suggest Shasta Daisy Leucanthemum x superbum, however the leaves are not typical of that variety.
I believe your suggestion of Oxeye Daisy / Leucanthemum vulgare is accurate.