Dark Wall #817
Dark CC BY-SA 3.0Just to prove my point, here is a slightly modified dark version.
Source Atle Mo
More Textures
Wide Rectangles #699
Wall CC BY-SA 3.0Simple wide squares with a small indent. Fits all.
Source Petr Šulc.
White Texture@2X #132
Light CC BY-SA 3.0Not the most creative name, but it’s a good all-purpose light background.
Source Dmitry
Cross Scratches@2X #626
Paper CC BY-SA 3.0Subtle scratches on a light gray background.
Source Andrey Ovcharov
Solid@2X #846
Gray CC BY-SA 3.0A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Background pattern 239 #2217
Red CC 0To get the tile this is based on, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Prismatic Curved Diamond Pattern 4 No Background@2X #542
Diamond CC 0Prismatic Curved Diamond Pattern 4 No Background
Source GDJ
geometrical pattern 01 remix #2456
Wall CC 0This is a remix of "geometrical pattern 01".
Source Yamachem
"Wide Stripe Wallpaper", Seamless Pattern #1227
Yellow CC BY-SA 3.0A seamless pattern with wide vertical stripes colored in pale yellow.
Source V. Hartikainen
Wood Background Pattern #882
Wood CC BY-SA 3.0A seamless background pattern with a texture of wood planks. This wood background pattern has vertically arranged planks. You may try to rotate it 90°, to see how it will look like when the wood planks are arranged horizontally.
Source V. Hartikainen
Mirrored Squares #123
Dark CC BY-SA 3.0Did some testing with Repper Pro tonight, and this gray mid-tone pattern came out.
Source Atle Mo
Decorative divider 187 #2522
Dark CC 0From a drawing in 'Studies for Stories', Jean Ingelow, 1864.
Source Firkin
Decorative divider 283 #1856
Dark CC 0From a drawing in 'In an Enchanted Island', William Mallock, 1892.
Source Firkin
"Glossy Pink Fur", Pink Background Pattern #1235
Pink CC BY-SA 3.0Here's a quite bright pink background pattern for use on websites. It doesn't look like a real fur, but it definitely resembles one.
Source V. Hartikainen
Green Fibers@2X #92
Dark CC BY-SA 3.0The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Prismatic Abstract Geometric Background 2 #268
Noise CC 0Prismatic Abstract Geometric Background 2
Source GDJ
Rocky Wall #41
Wall CC BY-SA 3.0High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Hoffman #1152
Wall CC BY-SA 3.0Did anyone say The Hoff? This pattern is in no way related to Baywatch.
Source Josh Green
Background pattern 232 #2297
Dark CC 0Heavily remixed from a drawing in 'Barbara Leybourne; a story of eighty years ago', Sarah Hamer, 1889.
Source Firkin
Floral design 88 #1876
Dark CC 0From a drawing in 'Cowdray: the history of a great English House', Julia Roundell, 1884.
Source Firkin
Diamond pattern 2 (colour 6) #2261
Colorful CC 0From a tile that can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Dimension@2X #1174
Light CC BY-SA 3.0Don’t look at this one too long if you’re high on something.
Source Luuk van Baars