Hemlock comes to mind, as with or without your proffered grain of salt, it can be eaten but is definitely not edible. Those defs are posted in a non-pedantic way above, incidentally.
Also, thanks for the chance to use the word ‘proffered’ in conversation, it’s vanishingly rarely used outside the legal field.
That’s OK, I didn’t have any desire to work for that asshole anyway…
Most folks are exponentially more productive when they don’t have to waste hours of their day (stressfully) driving/public transit from A to B just to do their job.