Today’s document related to Martin Luther King, Jr. is from the website set up by his descendants. I can’t put it up on my site because of their licensing rules, but you can view it on their site, The Martin Luther King Jr. Center for Nonviolent Social Change: a photo of Dr. King’s Children Viewing his Body for the First Time at the Funeral in April 1968.
There are many photos relating to King’s assassination at the Lorraine Motel in Memphis, Tennessee on April 4th, 1968: his entourage pointing at the direction of the fatal gunshot from the 2nd story motel balcony; his suitcase from the motel, the room being cleaned afterwards, the riots which followed his assassination, and the funeral itself. But I find this one the most moving because it is the one his family decided to post on their own site.
For an interesting article on the strict licensing rules of King’s material and the debate on whether the material should be public vs. private property because of its historical importance, see: I Have a Copyright: The Problem With MLK’s Speech at Mother Jones, which I found via Slate’s Vault twitter feed.