I haven't tried the Digging yet but after 34 codes, I have mostly cards between 1973 and 1975.
Biggest names would be 1974 Dusty Baker, 1973 Rick Reuschel RC, and a 1967 George Scott. Oldest card so far is a 1961 Zorro Versalles.
Lots more codes to enter... unfortunately the trading apparently doesn't start until April.