Here's a repeatable texture that resembles a light green concrete wall or something similar.
Source V. Hartikainen
A subtle shadowed checkered pattern. Increase the lightness for even more subtle sexiness.
Source Josh Green
Zero CC tileable yellow craft paper; scanned and made by me. CC0
Source Sojan Janso
Inspired by a 1930s wallpaper pattern I saw on TV.
Source Firkin
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
Nothing like a clean set of bed sheets, huh?
Source Badhon Ebrahim
Remixed from a design seen in 'Burghley. The Life of William Cecil', William Charlton, 1857.
Source Firkin
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
This background pattern contains worn out colorful stripes as a texture.
Source V. Hartikainen
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Prismatic Groovy Concentric Background 3
Source GDJ
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Actually, there's no clouds in it, but I think it looks quite nice.
Source V. Hartikainen
Here's an yet another background for websites, with a seamless texture of wood planks this time.
Source V. Hartikainen
Prismatic Groovy Concentric Background 4
Source GDJ
To get the tile this is based on, select the rectangle in Inkscape and use shift-alt-i.
Source Firkin
Number five from the same submitter, makes my job easy.
Source Dima Shiper
Used the 6th circle pattern designed by Viscious-Speed to create a print that can be used for card making or scrapbooking. Save as a PDF file for the best printing option.
Source Lovinglf
This one is amazing, truly original. Go use it!
Source Viahorizon
This is lovely, just the right amount of subtle noise, lines and textures.
Source Richard Tabor
This is the remix of "Tileable Wave Pattern 2" uploaded by "Arvin61r58".Thanks.I added a wire-mesh fence seamless pattern as a lower layer.
Source Yamachem
U.S.-based National Fire Protection Association standard fire diamond for flagging risks posed by hazardous materials. The red diamond has a number 0-4 depending on flammability. The blue diamond has a number 0-4 depending on health hazard. The yellow has a number 0-4 depending on reactivity. the white square has a special notice, e.g OX for oxidizer.
Source Firkin
Heavy depth and shadows here, but might work well on some mobile apps.
Source Damian Rivas
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
With a name like this, it has to be hot. Diagonal lines in light shades.
Source Isaac