It is possible that this plant could be a cranberry bush. It is possible that this plant could also be a blueberry bush. There is also a possibility that it is a mulberry bush.
Mulberry is a tree with berries. Raspberries and blackberries have thorns and berries. Many shrubs have berries and berry-like fruits. Check out the viburnums.
On your huge plant it could be a numerous amount of berries. The first could be blueberry's but it also could be; black berrys, rasberrys, strawberrys, gooseberrys, huckleberrys, hollyberrys.
Some berries can be poisonous. Without a description I cannot tell you what it may be, but I can offer you some advice. Do not eat any of the berries until you find out what they are.
There are myriad possibilities as to what kind of berry plant it could be. Many berries are edible, but there are many more that are unedible, even poisonous.