I didn't thoroughly check this out before I posted this. It isn't downloadable sewing patterns but archive scans of the patterns.
So if you already have a vintage pattern that is missing a piece maybe they will have a scan in this archive and you can recreate it.
If you are an experienced seamstress you could redraw the pattern to size i'm sure.
I'm sorry i didn't check this out before posting.
I'll try to be more thorough and not just blog happy!! :)
Commercial Pattern Archive is offering free access to their downloadable database of patterns for 1 week. The patterns are available from the years 1868-2000.
You'll want to hurry though the free week started August 19th and runs until August 25.
Log in information is username: guest password pattern
There are thousands of patterns so you might want to start NOW!! LOL
Strike that they say they have over 48,000 patterns!!!!
Thank you to Money Saving Mom for posting this!