I was briefly in Vicksburg in 1964 for a 1-2 week stint right after the Freedom House had been bombed. We were canvassing for the MFDP delegate election. I think the famous 1968 Democratic Party Convention was right after that, the MFDP affair there had a big impact on my political outlook.
In 1965 I hitchhiked across the US to training in Washington DC, where a lot of famous SNCC activists participated.
I got assigned to Canton, Mississippi, and worked in a small community called Valley View with 2 other summer volunteers, but I stayed on after they left until December, when I returned home to Seattle. I worked on school integration and the ASCS cotton board election, and went to more church than I've ever done. I knew Rims Barber of the Delta Ministries, and ran into Victoria Gray and her daughter quite a bit in the Canton Freedom House (which had also been bombed shortly before I got there)
After Mississippi, I had kids, raised a family, and got involved in various human rights solidarity movements around Chile, El Salvador, Guatemala, and Palestine. Now we live in Arizona and do humanitarian aid work on the Mexican border ("Tucson Samaritans")
I would say my experience broke me away from the academic or geek path I was going along as a "smart boy" growing up; I became committed to changing the US, rather than just a progressive observer. It was also at a pivotal time when the women's movement was emerging, and I carried back with me some of women's discussions about their role in the movement.