Now we're not sure what you'll be putting together, but this little box of tiny vintage brass screws might just be what you need to do it. There are 10 little screws in each little 1-inch by 1-inch little plastic box.
The screw measures a little over 1/2 inch long (about 4.5mm). The top slightly rounded, but at first glance seems flat. Use a slotted screwdriver. The heads are about 3/16 inch in diameter (about 6mm).
A few of the screws have a patina and look a little darker and hard to see in the photo.