This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
Subtle scratches on a light gray background.
Source Andrey Ovcharov
Prismatic Curved Diamond Pattern 2 No Background
Source GDJ
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Fix side and a seamless pattern formed from circles.
Source SliverKnight
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857. The tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
A seamless background colored in pale orange. It has a paper like texture with diagonal grid pattern.
Source V. Hartikainen
Prismatic Hexagonalism Pattern No Background
Source GDJ
From a drawing in 'Heroes of North African Discovery', Nancy Meugens, 1894.
Source Firkin
A background formed from an image of an old tile on the New York Metropolitan Museum of Art website. To get the base tile, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
You can never get enough of these tiny pixel patterns with sharp lines.
Source Designova
Turn your site into a dragon with this great scale pattern.
Source Alex Parker
You were craving more leather, so I whipped this up by scanning a leather jacket.
Source Atle Mo
This is a remix of "geometrical pattern 01".
Source Yamachem
This ons is quite old school looking. Retro, even. I like it.
Source Arno Declercq
Detailed but still subtle and quite original. Lovely gray shades.
Source Kim Ruddock
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
Remixed from a drawing in 'Works. Popular edition', John Ruskin, 1886.
Source Firkin
Same as gray sand but lighter. A sandy pattern with small light dots, and some angled strokes.
Source Atle Mo
A seamless background pattern of dark brown wood planks.
Source V. Hartikainen