1972 Silver Dollar

Little background first. My mother has been going to various banks over the last few weeks and getting her hands any and all old banknotes and 50 cent, 1 dollar coins that she can for me. I got to tell ya she is scoring a heck of a lot better than I usually do.

So I went over to my parents place today to pick through the new pieces she has obtained and one of them is a 1972 silver dollar, which struck me as odd. Knowing that 1967 was the last of the silver, except for those in sets. Even checked my recent edition of CCN to see if I missed anything, and 68 on is nickle. Magnet checked it and it is non-magnetic. So what do you all say? I am thinking cracked out of a set at one time.