How Do I Know What's Food?

I was looking at a strip of caulk that Amber had removed from the bathroom tile and started thinking, "hmmm, I bet Chloe would try to eat that." Dogs try and eat a lot of things. They are a lot like babies in that way. However, somewhere a long the way I learned that a lot of stuff was not for eating. Hamburger=Yum; Plywood!=Yum. But it isn't quite as simple as that. There seems to me to be a lot of material within the world that I would not conceive of eating and then another class of material that could perhaps be food but that I instantaneously think, "not food" based on life experience.