Formal and Official:
* Archive: A collection of historical documents or records preserved for their historical value.
* Repository: A place where documents or other items are stored, especially for safekeeping or preservation.
* Corpus: A collection of written or spoken materials, often used in linguistics or textual analysis.
* Canon: A recognized body of works, especially a collection of books accepted as authoritative in a particular religion or field.
* Codex: A manuscript bound together like a modern book, often used for religious or legal texts.
* Register: A formal record of items, especially one maintained by a government agency or institution.
* Database: A structured collection of data, often organized for easy search and retrieval.
Less Formal:
* Collection: A general term for a group of items brought together for a specific purpose.
* Compilation: A collection of materials put together in a systematic way.
* Anthology: A collection of literary works, especially poems or short stories.
* Compendium: A concise summary of a larger body of information.
The best term to use depends on the specific nature of the documents, their intended use, and the context in which they are being discussed.