Eventually, about 15 years after the war was over, people who held Federal notes, the greenbacks, could redeem them for gold coin. Few people bothered to make this trade because the war was long over, gold reserves were healthy, and people had faith in the government. Money was once again backed by real gold, but this created a new problem. The government could not print any more money that was not backed by gold, and that constricted the money supply. People who already had money, that is rich people, didn't want any more money added to the supply because an inflated money supply, devalues savings.
Inflation is always bad for people with money because their money becomes less valuable.
But people without money, especially poor farmers, were clamoring for the government to print more. Inflation always helps the poor because debts can be repaid in cheaper dollars and money becomes more available for loans, investments, for everything. Poor farmers were demanding an inflationary monetary policy. The Greenback Party dissolved in about 10 years, but a new party emerged and took up the inflationary baton. They were known as the Populist Party and legions of Midwestern and Southern farmers joined.