Pictures of sun rays you can likely find online, but who wants to go through the process of crediting someone when you can just make them yourself? =) I'll show you an easy way to create your very own sunbeam effect for your maps.
You Will Need...
RPG Maker MV
Photoshop or Gimp
Plugin: foreground.js - found within your game files!
You can probably use another version of RPG Maker as long as you find the right script. As for the plugin, any overlay plugin will work but I am using foreground simply because it's included within the game already.
My Sunbeams
Attached to this post are the sunbeams I made for this tutorial! Feel free to use them. Credit is nice (because you can make your own!) but not necessary. Note that these should only be used on 17x13 map sizes, or they might end up looking a little funny.