Ask your processor to double grind your "trim" with 20% beef or pork fat. Most of the flavor from meat comes from the fat. One of the "tricks" I do is to double grind my venison with bacon "ends and pieces" usually available from the grocery store for less that 1/2 the price of regular bacon. It adds a nice smoky flavor and who dosen't love the smell and taste of bacon? It really makes fantastic burgers this way!