Euphorbia lathyrus, the caper spurge - there's lots about this year popping up all over the place.

From Wikipedia:

"All parts of the plant, including the seeds and roots are poisonous. Handling may cause skin irritation as the plant produces latex. While poisonous to humans and most livestock, goats sometimes eat it and are immune to the toxin. However, the toxin can be passed through the goat's milk"

Careful!