Depending on season: Mushrooms (although I leave final ID-ing of some to my other half, as I am OK with the very common varieties, but less so with others!) brambles (blackberries),wild sorrel (known as soorock in Scotland), wild garlic, sloes (to make sloe gin), elderflowers and elderberries, blaeberriees.
At the beach: samphire, mussels and spoots (aka razor clams)