NFL Free Agency doesn't begin for real until Wednesday at 1:00 pm PT, but starting today at 9:00 am PT, the NFL's "legal tampering" period will begin, and this means that teams and agents can begin discussing parameters of new potential deals. They can negotiate, express interest, do all of that fun free agency stuff, but they cannot actually sign on the dotted line until Wednesday. It's a weird little rule.
Per NFL, this is what "legal tampering" means:
Beginning at 12 noon, New York time, clubs are permitted to contact, and enter into contract negotiations with the certified agents of players who will become Unrestricted Free Agents upon the expiration of their 2015 player contracts at 4:00 p.