ESPN first reported the news.
Lynch, who is currently a free agent, would provide more depth and competition for touches providing he returns to Oakland.
The backfield wasn't the only position addressed Thursday, as the Raiders strengthened the linebacker corps with a proven veteran.
Brandon Marshall joined the team on a one-year deal worth up to $4.1 million, per Rapoport. The team later announced the signing.
With Marshall, the Raiders have a player who knows the AFC West very well from six seasons with the Denver Broncos, where he contributed to Denver's win over the Carolina Panthers in Super Bowl 50. The 29-year-old Marshall provides a veteran presence to a young linebacker group consisting of Tahir Whitehead, Nicholas Morrow, Marquel Lee and Kyle Wilber, among others.