Some more diagonal lines and noise, because you know you want it.
Source Atle Mo
Looks like an old rug or a computer chip.
Source Patutin Sergey
Alternative 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
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
From a drawing in 'Resa i Afrika, genom Angola, Ovampo och Damaraland', P. Moller, 1899.
Source Firkin
This one is rather fun and playful. The 2X could be used at 1X too!
Source Welsley
Remixed from a drawing in 'A Child of the Age', Francis Adams, 1894.
Source Firkin
A light gray wall or floor (you decide) of concrete.
Source Atle Mo
Remixed from a design on Pixabay. To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
This is a semi-dark pattern, sort of linen-y.
Source Sagive SEO
Green Web Background, Seamless tile.
Source V. Hartikainen
A huge one at 800x600px. Made from a photo I took going home after work.
Source Atle Mo
A free web background image with a seamless concrete-like texture and an Indian-red color.
Source V. Hartikainen
A light brushed aluminum pattern for your pleasure.
Source Tim Ward
From a drawing in 'The Quiver of Love', Walter Crane, 1876
Source Firkin
Prismatic Floral Pattern 3 Variation 3 No Background
Source GDJ
The first pattern on here using opacity. Try it on a site with a colored background, or even using mixed colors.
Source Nathan Spady
Prismatic Snowflakes Pattern 3 No Background
Source GDJ
This was formed by distorting an image of a background on Pixabay.
Source Firkin
Seamless pattern formed from a tile that can be extracted by selecting the rectangle in Inkscape and using shift-alt-i.
Source Firkin
From a drawing in 'Chambéry à la fin du XIVe siècle', Timoleon Chapperon, 1863.
Source Firkin
From a design found in 'History of the Virginia Company of London; with letters to and from the first Colony, never before printed', Edward Neill, 1869.
Source Firkin