The woman claiming Soulja Boy fathered her kid has some hard evidence he's the daddy ... including pictures of her straddling Soulja.
Diamond Shantaniece Mackey filed legal docs claiming Soulja Boy has a son -- 5-year-old Portlon.
Turns out Diamond may have struck gold with a picture taken in 2007 in a hotel room where she claims she took a pregnancy test ... which came back positive.
