I think that Mr Asa is on the right track.
Those are Pan Head screws with ’rounded’ sides and star lockwashers which are common on the armature plate. The only other place that I can think of them is on the starter housing mounts, but those are larger, and there are three of them.
The control arm bracket screws and the air intake/silencer screws are usually Fillister Head screws with the ‘square’ sides.