Cannabis
Cannabis is everywhere. Legalized at the state level in 2014, it can be found in numerous forms at dispensaries throughout Portland. In some neighborhoods, its odor routinely mingles with exclamations of "Ooo, what a cute dog!" throughout the day. Public consumption is technically illegal, but this rule is quite thoroughly ignored. You can also grow it at home. Cannabis is similarly legal in Washington state, but not Idaho, which can inspire some cross-border purchases.
Other drugs
In February 2021, Measure 110, which reclassified the penalty for possession of many drugs, took effect. Now, the penalty for possession of an wide array of substances is just a civil violation. Additionally, the measure was intended to fund addiction and recovery services, party financed by taxes on cannabis.
How has Measure 110 worked out?
That depends who you ask. Despite the goals of this law, the government dysfunction I previously outlined has meant few people suffering from addiction have received the support and treatment they need. On the plus side, while it's not clear to me if governments in Oregon were paying much attention to folks tripping on mushrooms in the comfort of their own easy chairs, it's nice to know that this activity doesn't set up the weekend psychonaut for an afternoon in court.
Update, April 2024
Measure 110 was modified by a new law, House bill 4002.
The law puts in place a new misdemeanor penalty for possession of small amounts of hard drugs, with opportunities for defendants to avoid jail if they enroll in programs that aid in their recovery and potential treatment.
Read more about House bill 4002
Psychedelic Renaissance
In 2020 Oregon became the first state in the nation to legalize psilocybin (a.k.a. magic mushrooms) in therapeutic settings via Measure 109, which passed with 56% of the vote. So far, in practical terms, this hasn't amounted to much. It's uncharted territory for the state, and training and licensing requirements for therapists are expensive and substantial.
In May 2023, Oregon licensed the first "service center" for psilocybin assisted therapy. Therapists, sitters, guides, and friends have been providing unofficial therapy of this kind for decades, but Oregon's law is still on the bleeding edge, because it brings this therapy out of the shadows.