I know one thing I've looked for is the Close AM cent in 1998 & 1999 proof sets. 

In Memory of Crazyb0
12-26-1951 to 7-27-2020
12-26-1951 to 7-27-2020
In Memory of Tootallious
3-31-1964 to 4-15-2020
3-31-1964 to 4-15-2020
"If we continue to accumulate only power and not wisdom, we will surely destroy ourselves."
-Carl Sagan