Rookies were asked to arrive Thursday, a week before the full squad reports, for conditioning work and meetings. Practice starts next Friday when training camp opens.
Ferguson, the No. 4 overall pick, had an outstanding career at Virginia and is expected to start at tackle this season. Mangold, the No. 29 overall pick out of Ohio State, is expected to start at center. Talks with them should pick up next week.
All 10 draft picks missed the first day. But two signed deals later Thursday: Fifth-round selection Jason Pociask, a tight end from Wisconsin, and seventh-round pick Titus Adams, a defensive end from Nebraska.
The others who have yet to sign: Second-round pick Kellen Clemens, expected to challenge for the starting quarterback job; linebacker Anthony Schlegel; safety Eric Smith; receiver Brad Smith; running back Leon Washington; and cornerback Drew Coleman.
Nearly all those in attendance Thursday were undrafted rookie free agents.