I planted my potatoes near the surface so I could get the plants going quicker. Should I put a pile of wood chips on top of each potato, or build up the pile of wood chips as the season goes on?
You need to either mound the soil up over the bottoms of your plants or you could use straw and a tomato cage. Don't allow your potatoes to see the sun because then the skin of the potato turns photosynthetic and poisonous. Solanaceae, deadly nightshade?
Just keep covering the soil and potatoes beneath the foliage. Mounding it higher as the foliage grows taller. Why would a potato grow faster at the surface? That chunk of potato is what is used to get the plant growing until the green foliage is able to start making carbohydrates. Never eat green potatoes. Maybe you just carve off the green skin but I don't want to get sick.
Planting it close to the surface could dry it out too quickly. Are you doing this no till stuff? Or do you have fluffy plant beds? Check the pH of your soil. You want 5.5 - 6.0. Acidic. Same pH as blueberries like. Double dug beds have warm soil and with trenches the best drainage. Planting potatoes in pots with potting soil works real well and is easier to control the pH. Helps save garden real estate when rotation of crops has to happen.
When planting potatoes in cages with straw, you actually only allow 6 inches of top growth above the straw. As the potato plant grows you add straw to the soil below the foliage always leaving 6" of top growth. I do more like a foot.
Wood chips will use up any nitrogen that potato plant will need. As does straw. I just add fertilizer with even numbers, works great.