If you are really concerned about them, have a Doc check them out rather than asking here. A little hard to guess what they may be from your descriptions. They are probably normal, but for your own piece of mind have a Doc check them out.
Well the doctor has checked out em out before for a physical quit some time back starting my puberty years and I had these marks so they should of said something right.
But just wondering theres no way in hell these dark dime size spots on the head of my penis can be any sign of std or anything right?