Mexicana is one of the most famous Psilocybin strains that have been in use by Mazatec Shamans since Aztec times. Luckily, this strain produces Sclerotia, also known as Truffles. 

Effects for most people
This Truffle strain brings a rather soft high and is therefore ideal for beginners. Nonetheless, its potency should not be underestimated. 
- 5 grams give mild effects
- 10-15 grams can result in a medium to strong effect.

First effects are likely to be felt after around 15-30 minutes and and can last up to 6 hours. You can eat the truffles or make a tea of them (let it simmer for 20 minutes but don't pour boiling water, let it cool first).

*BE AWARE that these amounts are averages and can vary from person to person. Always start with a low dose.