Zig-zag pattern 4 #2415
Grid CC 0A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
More Textures
Rocky Wall #41
Wall CC BY-SA 3.0High detail stone wall with minor cracks and specks.
Source Projecteightyfive
Olive Green Web Background Image #1335
Green CC BY-SA 3.0Seamless Olive Green Web Background Image
Source V. Hartikainen
Stucco #294
Wall CC BY-SA 3.0A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
Concrete Wall 2@2X #80
Wall CC BY-SA 3.0A light gray wall or floor (you decide) of concrete.
Source Atle Mo
"Polished Stone", Gray Background Pattern #1053
Stone CC BY-SA 3.0A seamless gray background texture suitable for use on websites. To me, it has the look of stone. Feel free to modify it to meet your needs (by making it a bit lighter or darker, for example).
Source V. Hartikainen
Checkered Pattern #322
Grid CC BY-SA 3.0Simple gray checkered lines, in light tones.
Source Radosław Rzepecki
Prismatic Groovy Concentric Background@2X #450
Noise CC 0Prismatic Groovy Concentric Background
Source GDJ
Absurdity@2X #826
Light CC BY-SA 3.0Bit of a strange name on this one, but still nice. Tiny gray square things.
Source Carlos Valdez
Retro Circles Background 5 No Black@2X #427
Noise CC 0Retro Circles Background 5 No Black
Source GDJ
Background pattern 199 #2508
Green CC 0Inspired by a 1930s wallpaper pattern I saw on TV.
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