The Oakland City Council passed a resolution Tuesday night that decriminalizes certain natural psychedelics, including mushrooms, a move that makes Oakland the second city in the nation to do so.

The resolution instructs law enforcement to stop investigating and prosecuting people using the drugs. It applies to psychedelics that come from plants or fungi, not synthetic drugs like LSD or MDMA, also known as ecstasy.

After the vote, nearly 100 supporters rose from their chairs, clapped and cheered loudly.

“I don’t have words, I could cry,” said Nicolle Greenheart, the co-founder of Decriminalize Nature Oakland. “I’m thrilled. I’m glad that our communities will now have access to the healing medicines and we can start working on healing our communities.”

Councilman Noel Gallo said he introduced the resolution to the council after he was approached by Decriminalize Nature Oakland, a community group promoting natural psychedelics for mental health and overall well-being.

The resolution is a step toward legitimizing use of the plants for medicinal purposes, he said.

“My grandmother took care of us,” Gallo said. “She didn’t go to Walgreens to heal us spiritually and physically, she did it out of plants we use as Native Americans.”

Councilman Loren Taylor added an amendment that stated the approved resolution does not authorize commercial sales or manufacturing of the plants, possessing or distributing in schools or driving under the influence.

The amendment also clarifies that people dealing with depression or post-traumatic stress disorder should first see a doctor. It also stated that the use of natural psychedelics should be used in small doses for inexperienced users and “don’t go solo.”

Taylor said he worked with the Oakland Police Department and Decriminalize Nature Oakland to write the amendment.

More than 100 people crammed into the City Council chambers. Some people held bright, green signs that read “Decriminalize Nature.”

Dozens of people spoke in support of the resolution and said that it helped them deal with their depression.

“I wasn’t really living a life, I was so disconnected,” one woman said. “It was hard for me to survive everyday. It has helped me reach deep inside my soul and helped cure damage that had been done to me.”

Some people said that the psychedelic plants helped them with addictions.

“It was the most beautiful and life-changing thing that ever happened to me,” said a man, adding that he struggled with a heroin addiction.

Council president Rebecca Kaplan thanked the speakers for sharing their “deep and personal and profound” stories.

In the past year, Oakland police investigated 19 cases involving the use of mushrooms containing psilocybin.

“We want to be able to provide another medical service... to be able to help us at home and that is what this is all about,” Gallo said before last week’s public safety committee. “And it’s nothing new. It’s been happening for thousands of years in different countries, in different spiritual backgrounds.”

The Oakland measure would decriminalize mushrooms containing psilocybin, as well as the psychedelic plants ayahuasca, cacti and iboga. The measure is part of a wave of decriminalization efforts nationwide that some proponents call a “psychedelic renaissance.”

A ballot measure in Denver to decriminalize hallucinogenic mushrooms was approved earlier this month. Other statewide initiatives are brewing in California and Oakland.

Sarah Ravani is a San Francisco Chronicle staff writer. Email: sravani@sfchronicle.com Twitter: @SarRavani