The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Seamless pattern the tile for which can be had by using shift-alt-I on the selected rectangle in Inkscape.
Source Firkin
Super simple but very nice indeed. Gray with vertical stripes.
Source Merrin Macleod
Everyone needs some stardust. Sprinkle it on your next project.
Source Atle Mo
You don’t see many mid-tone patterns here, but this one is nice.
Source Joel Klein
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Remixed from a drawing in 'Hungary. A guide book. By several authors', 1890.
Source Firkin
Hey, you never know when you’ll need a bird pattern, right?
Source Pete Fecteau
I asked Gjermund if he could make a pattern for us – result!
Source Gjermund Gustavsen
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
Not the Rebel alliance, but a dark textured pattern.
Source Hendrik Lammers
Looks like a technical drawing board: small squares forming a nice grid.
Source We Are Pixel8
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Remixed from a drawing in 'Canadian forest industries July-December', 1915
Source Firkin
Classy golf-pants pattern, or crossed stripes if you will.
Source Will Monson
If you want png files of this u can download them here : viscious-speed.deviantart.com/gallery/27635117
Source Viscious-Speed
Like the name suggests, this background image consists of a pattern of dark bricks. It may be an option for you, if you are looking for something that looks like a brick wall for use as a background on web pages. It's not a masterpiece, but looks pretty nice when is tiled.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
This is so subtle you need to bring your magnifier!
Source Carlos Valdez