First, let me apologize for not mentionign that you were indeed involved in the Mississippi graves registration project. I think I knew that before hand somehow.
My information, probably from the same site that you got yours, was that he married Rachel McLaurin, probably in 1853 or before. Inasmuch as there were McLaurins in the regiment, that undoubtedly accounts for his willingness to transfer to the Mississippi unit.
High Bridge over the Appomattox River is reasonably close to Farmville, but well downstream of it. Every bit of information I have is that the Federal forces did not arrive in Farmville until mid-afternoon on April 7; in fact, their arrival interrupted the provisioning of Confederate units as they passed through the town. I suspect that Farmville may have been named as a place of capture because it was the closest town of any significant importance, and was the county seat of Prince Edward County. As Alan suggests, men who were captured at Sailor's Creek were sometimes said to have been captured at Farmville, and that is at least ten miles distant.
At any rate, Pearson is one more Mississippi soldier accounted for.