You say tomato.. but what is it?

I found a volunteer in my vegetable garden last year and took picutures of it. Another one has started growing this year. Image one shows the flowers (more yellow than white, the lighting is not great) and the "pods". The second image shows the fruit, lying on a bed of wilted lettuce. The third shows the fruit cut open. The blue object in images 2 & 3 is a standard size ballpoint pen, for scale.
Can anybody identify it? And is it edible, poison, or just unpalatable.

Regards
Ross

 

I say Tomatillo. They're not ripe until they fall off the plant, but they are edible.

 

I say Tomaillo as well. the fruit is encased in a sac and the leaves are monolobated.
It means little tomato in Spanish.