In pan, brown ground and onions together. Drain. Add mustard, ketchup and 5 of the cheese slices.
Unroll crescent dough; separate into 16 triangles. Arrange triangles in a circle on round baking pan with points towards the outside. (There should be a 5-inch diameter opening in the center.)
Place a medium scoop of meat to the widest end of the triangles. Top each scoop with dill pickle. Bring triangle tips up and over the concoction. Bake for 12 to 15 minutes. When done, place rest of cheese slices on top.
Optional: Place shredded lettuce and plum tomatoes in the center to serve.