today is the one-year anniversary of the sandy hook shootings in newtown, ct. twenty children and six adults were killed at the school. on opening day 2013, all major league teams wore a memorial patch for the victims of the massacre.
here are all of the examples i could find.
milwaukee brewers - 2013 topps khristopher davis
new york yankees - 2013 bowman platinum kevin youkilis
update - here are a couple more examples from other teams.
atlanta braves - 2014 bowman chris johnson (thanks jeff)