My mystery plant turned out to be Caper Spurge. It is a garden escapee on both coasts but I have never noticed it before.
Although it has a reputation for repelling moles and voles, it is very toxic to people and pets. I will keep it because it is pretty and evergreen during my tough winter. Maybe it repels deer, rabbit, and even voles and moles. Look, don’t touch.
Caper Spurge is a biennial, occassionally an annual, but this is my plant’s third year. It is setting a lot of seed, so I may get a colony next year. I have three right now.
Although used historically for several medicinal purposes, and as a poison to kill people, it is no longer recommended. It is said to have anti-tumor properties, and has been effective against acute lymphocytic and granulocytic leukemia, and further studies need to be done.
Caper Spurge is an attractive toxin, do not eat it!