The lawsuit was filed Wednesday in New Jersey's Bergen County, home of MetLife Stadium, the New York Post reported. The plaintiff, Eric Inselberg, names the team, quarterback Eli Manning and the Giants' dry cleaner, Barry Barone, who operates Park Cleaners in Rutherford, N.J.
Inselberg was indicted in 2011 on federal charges of selling bogus sports memorabilia. The charges were dropped after prosecutors said his lawyers had provided them with new information.
In court papers, Inselberg said he once discovered Barone in 2001 cutting up Giants' jerseys so he could repair the damage, making the items look like they had been used in a game.
Inselberg says a helmet in the Pro Football Hall of Fame, supposedly worn by Manning in the 2008 Super Bowl, is actually a fake.
The lawsuit says Manning and the Giants wanted to make money off the items, and Manning also wanted to hang on to his game souvenirs.
"This suit is completely without any merit whatsoever and we will defend it vigorously. We will not otherwise comment on pending litigation," a Giants representative said in a statement.