Per The Athletic's Mike Sando, one team executive said the Cowboys "had no intention of taking a receiver" until Lamb was still on the board at No. 17.
Per The Athletic's Jon Machota, the Cowboys were deciding between Lamb and LSU pass-rusher K'Lavon Chaisson when their spot came up.
Chaisson would have been a need-based pick for a Cowboys defense that lost Robert Quinn, who signed with the Chicago Bears after leading the team with 11.5 sacks in 2019.
Owner Jerry Jones told Machota they gave "serious thought" to Chaisson, but the appeal of Lamb, who was the sixth-ranked player on the team's board, proved too alluring to pass up.
"But as much as we thought of (Chaisson), and we thought a lot of him, CeeDee just took the day," Jones said.
The Cowboys had an opening at wide receiver after Randall Cobb left to sign with the Houston Texans as a free agent. They were bringing back Amari Cooper and Michael Gallup, who became the first Dallas duo to record more than 1,000 receiving yards each in a season since 2012.
Adding Lamb to that duo makes the Cowboys offense even more imposing heading into 2020. They led the NFL in total offense with 431.5 yards per game last season, nearly 24 more yards than the Baltimore Ravens at No. 2 (407.6).
Lamb was a big-play machine at Oklahoma in 2019 with 1,327 yards, 21.4 yards per reception and 14 touchdowns in 13 games.