For average circulated pieces I would say early-mid 1960-s. Around 1978-83 there was a dealer that I met at shows in the Kingsport, Tn. area who would bring me bags of 5000 for $65. Thru those years I bought close to 35-40 bags. He had S mints in them along with early teen D mints and others. Once at a show in Charlotte, N.C. I bought 8-9 wheat S mints and 5-6 Mem. S mints. 75 cents a roll for the Wheaties and 60 cents for the Mems. Those were good days.