Agreed, about trial and error, though I am already sufficiently prone to error that I like to at least understand what properties one should be looking for, to mitigate milk waste and ruined cheese! :-) Larger, non-poisonous leaves include those from thimbleberry, which are soft and sort of lavender scented when bruised; young balsam poplar (tough, possibly balsamy); burdock (sour); hops (bland); but aside from those, not many large leaved plants to be found here that I'd recommend...cow parsnip leaves can cause skin blistering, though probably have a sweet celery flavour; dandelion leaves may grow to a foot long, but have the brittle center vein full of bitter milk to rub off onto the cheese; maybe rhubarb leaves (sour) could work, because you'd have to ingest the actual leaves, in quantity, to have any ill effect. Hey...I wonder about using a birch bark mould/rehydrating container. Tanniny, non-poisonous.