I first read about Dahlia tubers being edible in James Wong's 'Homegrown Revolution' book, where he has a recipe for dahlia rosti.
I'd like to try them, but I love the flowers too much!
When I learnt about eating fiddlehead ferns, it had much the same effect on me as the thought of eating hostas had on poor Hostafan! It's cannabilism! (the last 'f' in pbff stands for 'fern' and I'm a total fern freak). Haven't had the heart to chop the new croziers off my lovely ferns just to eat them.
I have never tried eating Hostas either.
I do eat the fresh young leaves of the hawthorn in spring - they taste beautifully green and sappy.
Ramsons is a great seasoning in soups and anywhere else to replace garlic.
I like to use dandelion leaves and flowers in salads - the leaves must be young, as older ones taste very bitter.
Calendula, rose and dianthus petals are also added to salads, along with borage flowers and nasturtium flowers and leaves. Nasturtium flowers go brilliantly with pork, by the way.
Rose and dianthus petals and viola flowers are crystallised for cake decorating.
Lavander leaves and flowers are used in shortbread and for making lavender sugar.
I have eaten hemerocallis flowers and they're quite nice - a slightly spicy flavour.
Ground elder is supposed to taste quite good by all accounts, but haven't got round to trying it yet.
Himalayan Balsam seeds are edible too, apparantly not be missed, although fortunately I don't have any of it and I certainly shan't be looking for any!
I like Amelanchier berries, except that the birds get to them first most of the time!
Fuchsia berries are nice too - some species/cultivars taste better than others.