...
Sticky notes can be removed from paper documents and recycled, if they have no intrinsic value. If a sticky note provides contextual information or in any other way is worth keeping with the document, please leave the sticky in place and enclose it and the paper it is stuck to in an acid-free sling.
Greeting cards with "stuff" (glitter, felt, non-paper accents) should remain closed, be placed in a sling and can remain in the folder.
Specific formats often have their own preservation issues.
...