get random items form list

List<SPListItem> randomItems = new List<SPListItem>(); ;
foreach (SPListItem item in items)
{
  randomItems.Add(item);
}

Random random = new Random();

for(int i=1;i<needed;i++)
{
  int index = random.Next(0, randomItems.Count - 1);
  SPListItem randomItem = randomItems[index];
  randomItems.RemoveAt(index);
  // do something for randomItem
}

http://dotnetperls.com/list