I downloaded all of Scientific American. There is a k12 school website that posts the password to their group account, you can log into SA's own archives, and they provide them as PDFs. Only 2-3 issues from 1868 (I think) are missing.

Cell (journal) also makes all their stuff accessible, but they don't provide the front matter or cover... was going to grab that too. Quite alot of everything's up on archive.org if there's anything in particular anyone wants.