Can you eat coffee grounds

Probably not on its own, but as a composting material it can be used. Remember that creating your own fertilizer requires much more biomass then will be produced. So, coffee grounds with your orange peel and the bad bread will work. A truck full of coffee grounds, not as well. Building and using a composting bin will help a lot. Building it far from any Windows that may be open in the summer heat will help even more.