SAN FRANCISCO >> Thousands of misty-eyed revelers rolled like a summer fog over San Francisco’s Golden Gate Park today for the mind-numbing all-day festival of marijuana known worldwide as 4/20.

Crowds came to the famous Hippie Hill from across California to pay tribute to the smokable herb, which, for the first time since the annual celebration began, is being legally sold for non-medicinal purposes in the state.

“I feel it is my God-given right to use the tree of life,” declared Ezekial Galvan, 19, of San Jose, as he toked on a tree-sized joint, one of 100 he planned to smoke. “I’m going to pass out at the end of the day and have very nice dreams.”

The 4/20 celebration drew an estimated 15,000 people to Robin Williams Meadow on the east end of Golden Gate Park. Weed parties like this run into trouble in other cities because smoking cannabis in public is illegal under state law, but San Francisco officials decided to turn a blind eye to the smoke fest, even finding sponsors and issuing rules for the event.

Port a-potties ringed the meadow and few police were visible as the partyers got to work on their avocation, displaying a particular devotion to the old-fashioned doobie.

One man holding an orange box full of immaculately rolled joints shouted “pot, pot, get your pot,” like a hot dog vendor at a ball game, but most everyone already had the stuff. Still, vendors were everywhere selling tiny $5 gram baggies, cookies and gummies.

“It comes from the Earth,” was the sales pitch of Angel Carreno, 37, of San Jose, who was liberally dipping into the joints, edibles and bags of flower he was selling. “We’re not doing anything illegal here. It’s amazing!”

Jewelry maker Paula Morgado sold 420 Hippie Hill souvenir roach clips.

“We’re here to celebrate peace, love and the right to gather in a public place and do what we want to do without people telling us we can’t.” said Morgado.

Bear Waite, a paragon of sixties fashion with his long beard, tie-dye shirt and Chinese parasol hat, puffed on a giant inflatable joint as a sign of solidarity with the toking masses. He had already consumed his edibles.

“This is a revolution. It really is,” said Waite, 60, of Rio Linda, whose wife, Michelle, was relaxing on a blanket in the middle of Hippie Hill. “Any time people can get together without hurting each other is a good day. Sticks and stones may break your bones, but cannabis will never hurt you.”

As haze settled over the park, the lounging merrymakers were treated to recorded music playing from stage, including Jimi Hendrix singing Purple Haze.

“What a mellow crowd,” marveled Paul Warshaw, the CEO of the Greenrush.com weed referral service, which organized the event along with Sounds Bazaar and Haight Street Merchants. “The worst that’s going to happen is someone is going to fall asleep.”

Although the event was free, many saw the celebration as a business opportunity. Besides baggies of bud, joints and edibles, people circulated throughout the day with jewelry, crystals, meditation books and even hula hoops.

One featured attraction was the food court called Munchie Land. And a man named Bmoc was selling $30 sweatshirts saying “It takes the Haight to Stop the Hate.”

“This 420 is off the … chart,” he said, as the celebrants clamored for his merchandise. “I’ve never seen so much weed in my life!”

Betsy Walldinger, 64, who came all the way from New York, marveled about how times have changed compared to the days when her friends got busted on the street for carrying $5 baggies,

“This is a great day. It gets you away from all the BS,” said Walldinger as she sat on the lawn sharing a croissant with her chihuahua Sweetpea and breathed in the skunky air. “It’s an herb. God gave this to mankind.”