Well after further investigation of the pack of screws that came with my Antec 902 case, I became very puzzled. I am more commonly aware of hex head or round head with a washer like feature built into both these types of screws for the motherboard that goes into the standoffs.
So I assumed that the hex head washer type screw went into my standoffs. I also check if the threading matches by putting the screw into a spare standoff that is not installed into the case and screw it in gently with my finger as to not strip the threads and to know if the screw was meant for the standoff, or not. But to my surprise it wasn't.
There are only two types of screws that match the standoff perfectly with no hassle and fits easily. The first screw (which I only have three of and does me no good) is a rounded phillips head screw. The second type, which I have eight of and is the exact number of screws I need for my motherboard, is a pan head screw, which the head is flat and has a slight square shape to it. Both of these screws have no metallic washer type feature to them and aren't any type of motherboard screws that I'm familiar with. Are the pan head screws fine to use to hold down my motherboard and that the washer like feature is not necessary?
Does the shape of the screw head even matter? Or is it fine as long as the threading fits the standoff and that the shape of the screw head is irrelevant?