I got tired of using other people's parchment backgrounds and then trying to remember where i got them from.
So I made my own set. Most people may know this technique, but I surprise myself every day by picking up new tricks I figure I should have known years ago, and it's possible someone else may be in the same boat when it comes to this
Step 1: crumple and fold paper. 1 or two folds is plenty, I've also done some with map-style folding. your preference really. Leaving it crumpled gives mixed results, I find the paper falls apart when you try to unfold it after soaking. Plus if you soak it long enough for the colour to settle in, the crumples smooth themselves out for the most part. Still working on that.
Step 2: soak them in really (REALLY) strong tea. We have this really cheap loose leaf tea, it's almost like granules. I used 5 tablespoons to 2 cups of near boiling water, I wanted it to be strong, I'm not patient for this process I also made sure that the tea got into the folded areas.
Step 3: unfold then pat dry between 2 towels, and scan before drying. it's much easier when the paper is slightly damp, it stays very flat. I set mine to the highest setting it would go, 600 dpi (i miss my old one, 1200!) with colour setting of course. I then saved the image in a lossless format (PSD a la photoshop in my case) so I could always have a backup in case I mess things up. Then after running a few image effects (my original scan was very orange) I resaved the files to new locations. Voilà! Ready to be inserted/chopped/overlayed/further-grunged/whatevered at the artist's whim.
Also included are 4 scans for those without scanners. These are all saved at 5000x3900 (give or take the 3900 part) so they should be plenty big for most purposes (had to move them down a bit to fit in the forum constraints). If anyone wants originals, let me know and I can make them available through my FTP, they are approx 6000x5000 and 96 megs as PSD.
To make it official, I am releasing these textures into public domain with the Creative Karma License 1.0 -- Free to use for any purposes whatsoever without restriction as long as you do something nice for someone at some point