The following are primary sources that could add context to the book Blood on the River. In the past, I've had students read this book as part of a guided reading book group while also facilitating a DBQ called "Early Jamestown, Why did so many early colonists die?" . This works well for fourth and fifth graders - and the DBQ does have some great primary sources (including tree rings that show the "starving time").
I do think that, for some students, the DBQ was a little bit of a reach - so I think that further bolstering their understanding of how to use primary sources and giving them additional resources to practice close looking and add to their understanding of early Jamestown would be helpful.
This album contains these additional sources.