"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
More Textures
Fabric pattern (colour 3) #2400
Fabric CC 0Alternative colour scheme. Not a pattern for fabrics, but one produced from a jpg of a stack of fabric items that was posted on Pixabay. The tile that this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Prismatic Groovy Concentric Background@2X #450
Noise CC 0Prismatic Groovy Concentric Background
Source GDJ
Floral background 17 (colour 2) #1850
Orange CC 0Remixed from a JPG that was uploaded to Pixabay by theasad121
Source Firkin
Triangles #127
Dark CC BY-SA 3.0Dark and hard, just the way we like it. Embossed triangles makes a nice pattern.
Source Ivan Ginev
"Green Rhombuses", Seamless Background Pattern #1336
Green CC BY-SA 3.0A free green background pattern with a pattern of rhombuses on a seamless texture. Feel free to use it as a tiled background image on your web site.
Source V. Hartikainen
Prismatic Hexagonalist Pattern No Background@2X #804
Light CC 0Prismatic Hexagonalist Pattern No Background
Source GDJ
MBossed@2X #194
Grid CC BY-SA 3.0Embossed lines and squares with subtle highlights.
Source Alex Parker
Old Mathematics #43
Stripes CC BY-SA 3.0This one takes you back to math class. Classic mathematic board underlay.
Source Josh Green
Square ornament 26 #2590
Dark CC 0Square design drawn in Paint.net and vectorized in Vector Magic.
Source Firkin
Fabric 1@2X #10
Light CC BY-SA 3.0Semi-light fabric pattern made out of random pixels in shades of gray.
Source Atle Mo
Bright Multicolored Floral Background #559
Noise CC 0Bright Multicolored Floral Background by Karen Arnold from PDP.
Source GDJ
Green Fibers #91
Dark CC BY-SA 3.0The green fibers pattern will work very well in grayscale as well.
Source Matteo Di Capua
Flourish pattern (colour) #1737
Yellow CC 0Remixed from an image that was uploaded to Pixabay by Pixeline
Source Firkin
Always Grey@2X #54
Dark CC BY-SA 3.0Crossing lines with a subtle emboss effect on a dark background.
Source Stefan Aleksić
Prismatic Polka Dots 3 No Background@2X #529
Noise CC 0Prismatic Polka Dots 3 No Background
Source GDJ
Background pattern 314 (colour 3) #1837
Green CC 0The square tile this is based on can be had by selecting the rectangle in Inkscape and using shift+alt+i
Source Firkin
Decorative divider 247 #2077
Dark CC 0From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin