For peacetime usage, how about one that does Morel mushrooms? Those things are impossible to find until you see the first one or two in the season and remember how they blend in.
1. Detect the trees (I think morels are symbiotic with some kind of tree) that morels are most likely to be found near.
2. Detect the morels themselves, perhaps taking into account that you are now in a particular environment so you know you don't have to worry about detecting them on a sandy beach or some other ecological impossibility (if there is such a thing for morels, and I suspect there is).
I also hunt chicken-of-the-woods and dryad saddles which honestly are much easier to find and are, at least in my opinion, easier to cook and use. Dryad saddles are very nice as they have a fresh cucumber like taste. Need to get them 'young' when they are still spongy and not woody.
They were far and away the tastiest mushrooms I've ever had, different enough from the store bought variety to make the whole hassle worthwhile.