Acanthus mollis, also known as Bear's Breeches, Sea Dock, Bear's Foot Plant, Sea Holly, Railway Plant or Oyster Plant.....................this is a classic example of why botanical names are important. Researching this post, only three of those common names I recognize.
This is an incredibly resilient plant that grows from underground tubers, forming large clumps. Acanthus can be grown in full sun to full shade and looks great when naturalized under trees. The flower spikes appear in late spring and stand tall above the dark, glossy green leaves.
The drawbacks to this plant are that it needs to be cut to the ground after flowering to rejuvenate the plant, the flowers are also pretty sharp so care should be shown when attending to this. Acanthus and can become quite weedy, so attempt to keep the clumps contained.