Here are a few cards related to the holiday:
2009 Upper Deck Piece Of History Baseball #155 "I Have A Dream Speech"
I think we are all pretty familiar with King's "I Have A Dream Speech" but you might know that Bob Dylan played at the event before King's speech. He played the song "Only A Pawn In Their Game."
The Lincoln Memorial was of course the backdrop for the March on Washington in 1963 and so King and Lincoln go hand in hand.
2008 Upper Deck Goudey #237 Abraham Lincoln
If you ever get the chance to see the great PBS special called "The Meeting" I highly recommend it. It's a fictional conversation/debate between King and Malcolm x about their philosophical differences. I can't find a video of it online but here is a little clip from a stage production of it.
2009 Topps American Heritage #52 Malcolm X
2009 Topps American Heritage#C73 Robert Kennedy Chrome 0768/1776
Here is what Robert Kennedy said to a crowd shortly after Martin Luther King was murdered:
Two months later, Robert Kennedy would be assassinated as well.
2008 Upper Deck Piece of History Baseball #179 Civil Rights Act
Here's a video of the events leading up to the proposal of the Civil Rights Act by President Kennedy: