SWIM loves animals and sees this as kind of cruel, but stuff like this already exists, and not to offend anyone, but it's better to kill an animal rather than yourself. SWIM hopes he doesn't look like an asshole.
First, you do the basic testing methods like cracking the stem and seeing if a part turns blue, or making doing a spore print, looking for photo identification, etc. to check for obvious toxic shrooms to possibly save an animal.
Next you give the shroom to the animal and it'll (hopefully) eat it.
If the animal acts normal after it ate a lot and you waited like a week for toxic symptoms (Not sure, but some poisonous chemicals might some time) it's an edible, but not psychedelic mushroom.
If the animal dies, it's a poisonous shroom without a doubt.
If the animal acts in a strange way, it might be psychedelic, but just to be sure, keep it alive and give it one or more shroom meals. It wouldn't stay alive if it was poisonous, especially not after multiple meals. The LD50 of psilocybin and psilocin is rather high, so it would be fairly unlikely for the animal to die, if it is even possible for an animal to eat that much shrooms in one time.
SWIM hopes his idea is not dumb, as he was surprised to discover that nobody came up with a simple idea like this.