Symbolism, Imagery, Allegory
It's time to put on those sunglasses, because it there's not one but three (count 'em) suns in this play. So, what's the deal?
Richard and Edward want to know just that when they see these three suns in the sky. Richard says that the suns look like they're kissing and inseparable. We're not sure what suns look like when they're kissing, but we'll take Richard's word for it.
Luckily, we don't have to do much interpretation ourselves; Edward's here to tell us exactly what these three suns symbolize:
I think it cites us, brother, to the field,
That we, the sons of brave Plantagenet,
Each one already blazing by our meeds,
Should notwithstanding join our lights together
And overshine the earth, as this the world.
Whate'er it bodes, henceforward will I bear
Upon my target three fair shining suns. (2.1.34-40)
How sweet. So the suns are standing in for the three remaining York brothers (Edward, Richard, and George). Edward's convinced they will never be broken up.
Richard isn't quite as convinced. He thinks… oh wait, he doesn't tell us what he thinks they mean. He just says he doesn't think they stand for the York brothers. Maybe that's because he doesn't want to work with his brothers, and he wants the crown all for himself. Perhaps this lone wolf doesn't need to get any more buddy-buddy with the guys he's going to shove off on his way to the top.
On the other hand, he hasn't found out about his father's death yet, so he isn't even competing with his bros at this point in the play (that we know of). He might just not be that into his brother's idea. Maybe Richard just doesn't like being grouped with anybody; it's all about him, and he's in it for number one... and only number one.