If you know exactly who to give credit to, include that in the notepad, otherwise include that none of the items/meshes belong to you and all credit belongs to their rightful owners and creators, or something to that effect ;3 People do it all the time hun~
So you're just using objects that you've retextured?
You can use "All objects belong to their rightful owners" if the original owner(s)/creator(s) have not asked for personal credit in their release (i.e. "Please credit me if use is involved"). However, it is always polite to give credit to the source even if credit isn't requested. Whether it's a link to where you got things from, or a name mention (if you know), mention it.
As said before, people usually make text documents to provide credit in their .zip downloads for users to see as soon as they open it up. Maybe provide names and links to the source of the object/item. If you don't know of any names, then as long as you know you're permitted to use them, just provide a link to the source. In FH, a lot of people convert objects. If this is the case, then it'd be best for you to credit the game the objects came from (for example; WoW/Blizzard) and then the name of the user who converted them.
But most importantly, always check that you are permitted to use something, usually though the owner(s)/creator(s) written permission (to you personally, or publicly if it's open for public use).
Keep in mind:
If you don't know where it came from, who made it, or if the creator's license for said items includes rules saying not to, it's best not to use it.
In general, don't touch stuff you don't know anything about if you ever come across that scenario.