If it is Tanacetum, I found it too thuggish for a garden bed, from the one time I tried it in central OH. I took it out its' 2nd spring due to extreme exuberance. Might not be so wild in a more dry climate.

Thanks Jeb I thought it might be :)

It's definitely a crinum. A relative of amaryllis from Africa and often called the milk and wine lily.

Post on the Name that Plant forum where there are lots of experts in plant ID. [https://www.houzz.com/discussions/name-that-plant-dsbr0-bd~t_29966[(https://www.houzz.com/discussions/name-that-plant-dsbr0-bd~t_29966-dsbr0-bd~t_29966) It is helpful if you tell us where in the world this is growing (nearest large city).