Robert Plant says watching Willie Nelson give free weed away is one of his greatest touring memories.

The Led Zeppelin star was recently invited to play with Willie, 87, and he's revealed how the music icon would give away weed from the comfort of his touring bus.

Robert, 72, shared: ''The most cherished moment of my career was staying up for a couple of days. Not going home, just going to the next place. Finding that I was in transit forever.

''We were invited to play with Willie Nelson a couple of months ago and he was travelling through his tour with his big bus giving away weed to everybody.''

Asked how Willie goes about giving it to other bands, Robert told the 'Digging Deep' podcast: ''He just gives it away. It's a truckload from here to the ... mirrorball and beyond. Free. With doors to go in, get your little hit and go out the other side.''

Robert has achieved enormous success during his career, but during his teens, his parents were eager for him to pursue a more conventional working life.

He said earlier this year: ''I had my moment of professional potential, and because I didn't accept it I had to leave home when I was seventeen.

''So I toughened up pretty quickly. I made my peace with my parents a couple of years later. But it was good, it was what it should be.

''I know so many guys from my time at school, who I still see and who are very funny and love life, but they did the wrong thing. They stuck with a family or whatever you were supposed to be doing, and they really rue the fact that it never really kicked in.

''They didn't live their life, they lived the life that was required.''