Reuel Colt Gridley (January 23, 1829 – November 24, 1870) was an American storekeeper who gained nationwide attention in 1864, when he repeatedly auctioned a plain sack of flour and raised over US$250,000 (equivalent to $4,870,000 in 2023)[2] for the United States Sanitary Commission, which provided aid to wounded American Civil War soldiers.

He made a bet with a Republican friend that the loser would carry a fifty-pound sack of flour through the town.

He performed his punishment with the accompaniment of the town band, and at the end someone offered that the sack should be auctioned off to raise money for the Sanitary Fund, a new organization that aided disabled Civil War veterans.

When nearby Virginia City, Nevada heard of the event (and where young newspaper editor Mark Twain was working at the time), they invited Gridley to come there, which he did.

These bidders added around $170,000 to the Sanitary Commission's fund, and within twelve months Gridley had more than $250,000 with his sack of flour.