Question: I would like to know if the fruit that looks like the blackberry is edible? The stems are very thorny and are growing wild in my garden.
Answer: To be certain that what you are describing really is a blackberry (Rubus fruticosus), we would need to see a photograph.
However, blackberries are very efficient self-seeders and are very thorny indeed, so it sounds as though you have this delicious fruit in your garden.
They freeze well if you find you can’t keep up with the supply.