Tradition of my country insists they like to dwell under fly agaric, although by this time of year those may be gone. Said organism has a symbiotic relationship with silver birch so if you have any of those where you live it'd be a good place to start.
Fairies have an aversion to iron so don't carry anything made of that with you. I don't know what they eat, if anything, but I expect natural things like seeds and fruit would be plausible, although chances are they have their own food and thus no reason to risk approaching a human.
I'd personally leave any object somewhere away from civilisation and if it has moved or is no longer present, something has done something with it, and one could say that something to be a fairy. How from knowing where they are you would actually come to speak with one I wouldn't know, but I don't expect it possible.
I understand this thread is probably a joke but we could all do with some phantasm to follow.