Lamb told Mike Silver on the Open Mike podcast that he was working out when he saw the news.
"I was actually in the gym. I saw it. It was on TV. I was working out in Fort Lauderdale in my offseason program, and I saw it on TV, and I was like, 'Wow, that's crazy,'" Lamb said. "And then my phone started blowing up literally minutes after. It's been a crazy story ever since."
Despite being caught "by surprise" by the Cooper trade, Lamb said he's ready for the challenge.
"That's a lot to take in. It kind of happened so fast, but I feel like that's a situation I'm ready to take on," he said of being the No. 1 receiver for the Cowboys. "Honestly, it kind of, in a sense, raised the standard. Obviously, I hold myself to a high standard already, but obviously, at this moment, there's nothing else you can really do but take it on. That's the energy I have."
Lamb played at a Pro Bowl level in his second season, netting 1,102 yards on 79 catches with six touchdowns. The Cowboys' confidence that the 23-year-old can handle the attention that comes with being the No. 1 receiver allowed them to trade Cooper's $20 million contract for a fifth-round pick.
Lamb said he texted with Cooper after the trade went down.
"Just wanted to thank him for everything he had done for me in the first two years," he said. "Those are real important to me and my direction and trying to find a place in this league where there's a lot of great receivers. A lot of guys who do a lot of things well in this position. Just giving him his roses for taking me under his wing."
Now Lamb is ready to fly as the big dog in Texas.