function findSomething() 
  foundAnything = false
  for i = 1, 16 do
    Data = turtle.getItemDetail()
    if Data ~= nil then
      turtle.select(i)
      foundAnything = true
      break
    end
  end
  return foundAnything
end

findSomething()
turtle.placeDown()
while turtle.forward() and findSomething() do
  turtle.placeDown()
end