FOXBORO — Second-round pick TreVeyon Henderson was the only draft pick absent for the start of Patriots rookie minicamp on Friday.

It’s unclear why Henderson was not present for Friday afternoon’s session. He was not among the Patriots’ draft picks who signed their rookie contracts on Friday, but other players who remain unsigned, like left tackle Will Campbell and safety Craig Woodson, were present and participating.

It wasn’t only Patriots rookie on the field Friday. Wide receiver John Jiles and cornerback Miles Battle were among veteran players participating in the rookie minicamp session. Jiles was among Friday’s standout players. Head coach Mike Vrabel, who was getting into the mix and playing linebacker, was excited when he saw Jiles make a high-point snag near the end of the session.

Vrabel spent time with edge defenders, tight ends and quarterbacks and got hands-on with special teams work, as well.

Campbell played left tackle, while third-round pick Jared Wilson lined up at center. Seventh-round pick Marcus Bryant, who started at left tackle at Missouri, took snaps on the right side. Fullback Brock Lampe, who’s 6-foot-1, 249 pounds, also saw some time at tight end.

With Henderson out, undrafted rookie Lan Larison took a bulk of snaps at running back.

Executive vice president of player personnel Eliot Wolf, vice president of player personnel Ryan Cowden and personnel executive Alonzo Highsmith were among front-office members taking in the practice session.