One can teach oneself to identify edible mushrooms even if one does not have someone more knowledgeable, but there are some principles to keep in mind:
First, you need multiple field guides with lots of photos. Ordinary wild plants are usually quite uniform in their appearance, but a mushroom species can exhibit a lot variability in it's appearance. Just pick up two different field guides and compare the photos for a given mushroom species and you'll see that they often look very different, even though they are the same species and from the same region. Mycology websites usually have photos you can consult and the people on their message boards are usually keen to help you identify your mushrooms. So you need multiple visual references. Never rely on just one "definitive" field guide, or someone's YouTube videos. I've seen some worrisome misidentifications online by people who, like me, are still new to mushroom identification.
Second, never consume a mushroom unless you're certain of what it is, and even then, the procedure is to take it home, cook up a small piece, and eat it only that piece. The next day, if you've experienced no ill effects, you can eat a whole mushroom, not a plateful! Tell someone you're test-sampling a mushroom so that they will know what's happening if you suddenly take ill and can't seek medical help yourself. The worst approach is to go out foraging and sample a mushroom without having properly sampled it as described above. I you misidentify a sought-after species while in the wood you could be incapacitated while far from help and could easily perish.
Third, cook your mushrooms before eating them. Besides the fact that wild mushrooms can be covered in bacteria (think of it like drinking unfiltered lake water), mushrooms are chitinous and must be cooked for the nutrients to be absorbed into your body. Raw mushrooms, while tasty, mostly pass through you without imparting any nutrients.
Fourth, stick to mushrooms that are easy to identify and have few or no toxic look-alikes until you build up a confident mental store of correct identifications. The species my wife and I are most comfortable identifying with ease here in Ontario are: giant puffballs, chanterelles, shaggy manes, chicken-of-the-woods, dryad's saddle, and oyster mushrooms. There are enough of these around (from early summer into autumn) to make mushrooming worthwhile for us. Naturally, the list of sought-after mushrooms in your area (that don't have lethal look-alikes) may be different from ours. The much coveted morels aren't on my list simply because I have never come across any yet.
Hope this helps and happy foraging,