Cod Liver oil, Tuna fish, Shiitake and button mushrooms are some of the foods that are high in Vitamin D. Fortified cereals, Oysters, Caviar both black and red are good sources of Vitamin D. However, sunlight is the greatest source of Vitamin D to your body.
The blubber of walrus, seals and whales is a tasty, but not widely available, source of lots of D, which is actually a pre hormone not a vitamin. Wild salmon, especially sockeye (red salmon) is a practacle sourse. Farmed salmon has only 1/4 as much. Any other oily fish is high in D as well. An easy and inexpensive way to be sure you're getting plenty of D3 is to take a supplement or if its an option spend time in the sun.