When you bring produce home from the store, wash it before you peel and trim.  Then place all peels and trimmings into a zip lock bag, and pop them in the freezer.  They can be added to water along with meat or poultry scraps to make the best homemade soup stock.  I keep a bag of onion peels, carrot peel, celery tops and scraps, and potato peels in the freezer.  When I get enough, I cook them up to make vegetable stock, or add my meat scraps or bones for extra flavor.  Once the stock is done, I strain off all the scraps and use the stock to make some of the best home made soups and stews.