On a crisp autumn Thursday, the Patriots went back to work on their practice fields behind Gillette Stadium. The team wore shells again.

Rookie defensive end Michael Buchanan returned to action after missing the previous session for non-injury reasons.

However, three players were still not on the field. Running back/return specialist Leon Washington (ankle) and defensive tackle Tommy Kelly (right knee) missed their second straight workouts, while rookie linebacker Jamie Collins wasn't seen. It was his first missed practice of 2013 and it's unclear at this point exactly why. Collins was not among the 16 Patriots listed on yesterday's injury/practice participation report.

Meanwhile, running back Shane Vereen (left wrist) and first-year defensive tackle Armond Armstead (infection) were observed heading to the practice fields, presumably to watch and/or work on their rehabilitation exercises. Vereen is on IR/designated-to-return and won't be available for game action till at least the Carolina contest next month.

Armstead, though, is interesting because next week is the first opportunity that players like him on the non-football injury (NFI) and/or physically-unable-to-perform (PUP) lists can begin practicing again, if medically cleared to do so. Perhaps his appearance in front of the media was a tacit indication that he's close to returning. He has been out of commission since mini-camp in June.

Player interviews will take place after practice, early this afternoon.