Can you buy straight from the U.S. Mint?

I'm curious to know, for those interested in investing in physical currency, is it possible to purchase directly from the U.S. Mint? I understand that the Mint is responsible for producing and distributing official U.S. coins and currency, but does it also offer a retail service for individuals to buy directly? If so, what are the procedures and requirements for making such a purchase? Would this be a secure and cost-effective way to acquire genuine U.S. currency? Clarifying these points would help many investors interested in expanding their physical currency holdings.