I never saw "Mississippi Burning" but it looks like they have the opposite problem these days. Ouch.
Here are some Mississippi Red Cross websites, which also have some donation links at the sites:
Adams County Chapter of the American Red Cross
http://www.adamscountyredcross.org/
Oops, that's the only Miss. RC site which mentions Katrina AND has an evident donation button/link, I see. Oh well, so much for preparation and organization. --Here's the American Red Cross general donation link then, https://www.redcross.org/donate/donation-form.asp . That should do.
And here's the American Red Cross Southeast Louisiana Chapter, http://www.arcno.org/ ...whoops, there you actually have to create an account to make a donation. Sigh.
Well, the sites are informative if nothing else. At least they still exist, showing the servers haven't washed away, so that maybe Misty May and Kerri Walsh will have a beach to play volleyball on after all...