It's the Chicory root that is dug up (in the autumn), sliced, dried, roasted, ground and added to coffee. I have tried it but my digestive system said, "Please don't do that again." Chicory root contains inulin which is a dietary fiber. For some people it may cause some discomfort until the body adjusts.
But like anything that may cause a bit of a tummy ache, I have learned to try again. Since inulin is beneficial, start with just a pinch in some boiled water and call it Chicory tea. If that works, gradually work up the the 'grown-up' version.