I collect a shopping bag full of elderflowers from Brabyns park every year to make cordial & sometimes champagne.
The woodlands around the site of Marple Hall ruins near Marina Drive & Marple Hall Drive are good for wild garlic - just follow your nose!
Behind the substation on Union road has loads of what I think are wild musk roses that yield masses of rose hips. I think these can be used to make tea & jam with.
The footpath from Manor rd known as 'Seven Stiles' used to have loads small of beech trees which of course give beech nuts. Think these need some form of soaking or cooking to make them safe to eat.
It's not exactly foraging but I have a big, old, apple tree in my garden. I get maybe 100kg+ of apples that end up spoiled, (there's only so much I can use!). If you or anyone else could use them, I'd be happy to see them being used.