A lot of people generally keep anything 1959 and prior. I personally keep everything 1955 and prior. One to look for is the 1950D, it is the key of the series. Also the war nickels, which as stated in the prior post is 1942 thru 1945 with the large mint mark above the dome of monticello. Just a word of note though, there are some 1942 nickels out there which are not silver (war nickels). These do not have the large mint mark above the dome. All of the 1943 - 1945 are silver war nickels. Another to look out for is the new "buffalo" nickel that just came out a couple of years ago. There is a error coin called a "speared bison" which has a die crack from the top of the coin thru the middle of the torso of the bufallo down towards the bottom of the coin, basically looking like the animal has been speared. These can be worth several hundred dollars.