You mentiond a wire mesh, held just off the ground. It is a good idea to cover it with a cage (look up 'ground feeder'.) This keeps the bigger birds from helping themselves to everything. My pigeons happily peck around the edges but cannot take from the little birds' food.
Another trick that has helped the battle with magpies is that I have put the hanging feeders just tucked under the rambling rose bushes. The little birds can help themselves but the magpies are afraid of entangling themselves in the branches. Problem solved!!