The Google has conflicting answers. I come from a background of "everything goes in the garbage disposal", my wife's background is "never put anything in the garbage disposal". I suspect reality is somewhere between us.  Note: I'm talking about the garbage disposal unit under the sink. 
If you have a septic tank, avoid using the garbage disposal, especially for anything like egg shells, bones, coffee grounds, and other things that the bacteria in the tank won't eat.  Worst case scenario is that they can plug up your leach field for a very expensive repair. 