The unit cell for this seamless pattern can be had in Inkscape by selecting the rectangle and using shift+alt+i.
Source Firkin
Continuing the geometric trend, here is one more.
Source Mike Warner
A blue background wallpaper for websites. It has a seamless texture with vertical stripes. It looks quite nice not only when using as a tiled background on websites, but also on computer desktops.
Source V. Hartikainen
Background Wall, Art Abstract, white Well & CC0 texture.
Source Ractapopulous
Subtle scratches on a light gray background.
Source Andrey Ovcharov
A seamless pattern formed from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
Remix from a drawing in 'Ostatnie chwile powstania styczniowego', Zygmunt Sulima, 1887.
Source Firkin
Luxurious looking pattern (for a T-shirt maybe?) with a hint of green.
Source Simon Meek
From a drawing in 'Sun Pictures of the Norfolk Broads', Ernest Suffling, 1892.
Source Firkin
This one is so simple, yet so good. And you know it. Has to be in the collection.
Source Gluszczenko
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
A background pattern with green vertical stripes. A new striped background pattern. This time a green one.
Source V. Hartikainen
A seamless pattern drawn originally in Paint.net by distorting a slice of background pattern 116 and copying the resulting triangle numerous times.
Source Firkin
Horizontal and vertical lines on a light gray background.
Source Adam Anlauf
Nice and simple crossed lines in dark gray tones.
Source Stefan Aleksić
Remixed from a PNG that was uploaded to Pixabay by VictorianLady
Source Firkin
Prismatic Groovy Concentric Background 3 No Black
Source GDJ
You could get a bit dizzy from this one, but it might come in handy.
Source Dertig Media
Embossed lines and squares with subtle highlights.
Source Alex Parker
From a drawing of the coat of arms of the Ottoman Empire on Wikimedia.
Source Firkin
Formed by distorting the inside front cover of 'Diversæ insectarum volatilium : icones ad vivum accuratissmè depictæ per celeberrimum pictorem', Jacob Hoefnagel, 1630.
Source Firkin