Data file for Wonderous Items
 

I am just starting to investigate custom options and want to look through existing wonderous items. I cannot find which data file I need to open to see the wonderous items from the PHB. Any help?

Many (if not most) of the items in the PHB are also part of the SRD, which is included in Hero Lab's 5e package. Unfortunately, we don't have direct access to the datafiles for anything in the SRD.

But that is why the editor has "New (Copy)" that allows you to make a copy of the Thing you want to look at or to copy from. ;)

Of course! I should have mentioned that. OP, as ShadowChemosh says, you can figure out specific items you want to look at, then pull them up in the editor using that New (Copy) button.