I live in Queensland, Australia, and I have quite a lot of experience with Magic Mushrooms, having picked and taken them upwards of 10 times now. The type we get here are your typical/proper 'Gold Tops' (Psilocybe Cubensis).
Believe it or not, they are VERY easy to identify, and you would have to be downright stupid to mistake one of the deadly types, such as Death Caps, for a Gold Top. And yes, we do have a handful of the most toxic and deadliest Mushrooms growing here (this is Australia after all).
The easiest way to identify a Gold Top, is by it's....Gold top! It's not actually golden, but moreso tan, and it will often have a 'nipple' on the top. If your suspect Mushroom does not losely fit this description, do not bother further examining it, because it's most likely going to be toxic, and there's a 99% chance it's not going to contain Psilocybin or Psilocin. If your mushroom fits this description, gently break it off at the very bottom of the stem, and then proceed to bruise and/or crush the stem with your fingers. If you have an actual Gold Top, you will see the stem turn a shade of Blue/Black where it has been bruised and broken. This can take anywhere from 10-15 seconds to 15 minutes.
Usually the more potent Gold Tops change colour a lot faster, and this is due to a chemical reaction between the Psilocybe/Psilocin and Oxygen.
The above properties are the main indicators as to whether or not you have an actual Gold Top. You really don't need to check anything else from here, but if you're paranoid, here are a few more safety measures you can take.
1) Gold Tops
may have a 'ring' (annulus) 3/4 of the way up the stem, so don't freak out if your Mushroom has one
2) Check the 'gills' underneath the cap - Are they brown/dark in colour? If so, that's good! I would not touch them if they had White gills!
3) Does the Mushroom have a 'cup' like growth at the bottom? They usually losely cover the bottom 1/4 of the Mushroom, and are almost always an indicator that the Mushroom is toxic. These 'cups' grow on virtually all of the most toxic Mushrooms, such as the amanitas. What I mean is, never eat a wild mushroom with a 'cup', since it'll probably kill you.
That's about all I can tell you off the top of my head. I hope I have answered your question well enough, and if I haven't, feel free to ask away.