DrGreenthumb
Bluelighter
Yes, they're easy to identify, that's why it's easy to be sure you have the right ones. You shouldn't eat any mushroom without knowing what it is. AFAIK you're right & there aren't any poisonous mushrooms that look much like liberty caps, at least in the UK, you'd have to have no idea what a liberty cap looked like to pick a deadly mushroom. There are a few related & probably inactive (or at least weak - possibly nausea inducing) psilocybes that look similar, but they don't have a nipple, slightly different shaped cap.