A "working paper" does not mean "a manuscript I've been working on". It refers to a paper that has been published in venues designated for disseminating preliminary research reports. These venues are often (but not always) internal to a department, and they are rarely peer-reviewed (usually they are reviewed only by the editors). See the Wikipedia entry on Working paper. In conclusion, you cannot call your manuscripts "working papers" if they haven't been published in such venues.
The best you can do is to call them "manuscripts", because that's all they are. They're not submitted, under review, under revision, or anything like that. I personally wouldn't pay any attention to entries on a CV that say "manuscript", as there is no way for anyone to know if these manuscripts even exist. What's worse, it looks like CV padding.
I also don't care much for CV entries that say "submitted" or "under review". Anyone can submit anything and have it reviewed, so it says nothing about its quality. I wouldn't list any paper on a CV that either (1) hasn't been published, or (2) hasn't been accepted for publication.