Potato yield

So this is what I harvested out of our potato box yesterday. Not as much as I had hoped for. It's weird because the tubers all seemed to grow in clumps around the top of the soil.  I think next year I will need to dig out the soil a good deal into some sort of bin so I can bury my seed potatoes deeper and cover them up more.  This will hopefully increase the yield.  We'll see, still learning...