Mmmmm...interesting & controversial. I'm personally a bit undecided - erring on the yes they'd know generally but what if a bunny had lost too many of its natural instincts & made poor choices (special needs bunny). I'd worry about the foxglove family with any rabbit. Do they "know" by taste & smell? I've noticed differences in how my bunnies are with new foods. Boo storms in & eats anything edible, Joey has a "taste". House plants can be toxic to house rabbits so they dont know not to eat them. Maybe they will eat safely when they have choice & access to a range of forage as they do in the wild? A few times I've found a stray unidentified leaf on the floor when a huge pile of forage has been scoffed which leads me to think mine "know". When I got my forage ID all wrong they also left the buttercups I thought was something else . Clever rabbits!