Commissioner Roger Goodell confirmed Tuesday at the NFL Annual Meeting that the Miami Dolphins were another of the teams, and The Morning News reported the San Francisco 49ers and Cleveland Browns also are believed to have violated the rule. All four of those teams have new head coaches or coordinators.
NFL Network's Albert Breer reported Friday that five teams were assessed fines on March 18 and have filed appeals.
According to the Morning News, several Cowboys players mentioned meeting with new defensive coordinator Rob Ryan to get a head start on learning his system.
NFL general counsel Jeff Pash said the violations aren't related to the league's lockout of players, which began March 12, hours after negotiations broke off and the union dissolved. Even during normal offseasons, from the end of one season until around March 15, NFL rules bar teams from holding organized workouts, practice or meetings, and don't allow position coaches to supervise players.
"It's a 'go home and relax' period," Pash said.
Since the lockout began, no contact between the league's 32 teams and players has been allowed. Players aren't paid and can't negotiate new contracts. They also aren't allowed to use team facilities.
The Associated Press contributed to this report.