The company is also selling Apple's iTunes gift cards at Hallmark stores.
Hallmark's seven-city "Use Music Summer Tour" visits music and summer festivals around the country, starting with McGraw's concert in Atlanta on Saturday and ending in Las Vegas on Sept. 9.
The road show includes a Hallmark interactive area letting consumers listen to Hallmark's Cards with Sound and engage in other exhibits and interactive kiosks.
Contest entrants can perform on a sound stage at the Hallmark tent, and winners at each local event will have their performances posted on hallmark.com/. Finalists' videos will be posted on Sept. 11, and consumers will be able to vote for their favorite performance through Sept. 18.