It is already known how successful was Portugal's government decision to decriminalize drug use and instead of using force to give treatment to drug addicts.
Portugal decriminalized all (or most?) drugs and people are now allowed to posses certain amounts of drugs like is mentioned in Wikipedia:
Amount limits of possession for personal consumption are:[22]

25 g Cannabis (herb)
10 g Opium
5 g Hashish
2.5 g Cannabis Oil
2 g Cocaine (Hydrochloride)
2 g Morphine
1 g MDMA
1 g Heroin
1 g Methadone
1 g Amphetamine
0.5 g Pure THC
0.3 g Cocaine (Benzoylecgonine)
0.1 g PCP
500 µg LSD

But I see here mainstream stuff. I'm more interested in safer psychedelics such as DMT (in combination with peganum harmala), salvia or magic mushrooms but I see no of them being mentioned. I would appreciate if someone knowing well Portugal laws would answer because I can't find in english allowed amounts.

From what I can find, you can possess up to 10 days worth of any substance--which seems like it's up for interpretation.

I really don't think anyone's going to be raiding your place if you have a few extra grams of mushrooms or DMT; I think the distinction is primarily for those who are clearly selling large quantities of drugs. To play it safe I would call up your local agencies and ask them, as I'm sure there's an arbitrary number written down somewhere that you can use for reference.

Yes, it's true that up to 10 days so problem is going to be if authorities see you as dealer.
There must be expanded list of drug regulations but probably it's going to be in Portuguese language what complicates search.
I found something about salvia but not sure what they mean by new substances:

"Portugal
A law enacted by the Ministry of Health on April 17, 2013, prohibits the production, importation, exportation, advertisement, distribution, sale, possession, or availability of new psychoactive substances (including Salvia divinorum)."
http://www.sagewisdom.org/legalstatus.html

I certainly hope salvia is not illegal amongst all that other stuff.

If cocaine, heroin and similar addictive junk is legal salvia should be legal. But again politicians are dumb enough to drug society with alcohol and tobacco that make a lot of damage.