I have tentatively identified this tree as a species or sub-species of the hack berry tree family. However I am not a botanist and may well be incorrect in the identification of this (Celtis occidentalis).
The berries are approximately one quarter to one half inch in diameter. They have a dark purple to black color and grow individually or in pairs.
The bark on the tree is rough and shows deep fissures.
This tree seems to have a large number of berries on it. I have not tasted the berries because I do not know if they are poisonous or non poisonous.