Wiktionary
plain paper
n. Paper that has no markings on it, usable paper.
Usage examples of "plain paper".
The money was underneath the folded garments, in neat bundles wrapped in plain paper and sealed with tape.
Out from behind her back she brought a bunch of roses, wrapped in the plain paper of a local flower shop but still showing the full glory of the new summer in their white and pink petals.
He did it on a piece of plain paper from the oice and it was short and to the point.
We'll either get him with this or not at all On plain paper, double-spaced, two carbons.
He didn't just pack the book, he packed a sheaf of plain paper, some pens, even ink.