A seamless pattern based on a rectangular tile that can be retrieved in Inkscape by selecting the rectangle and using shift-alt-i.
Source Firkin
A repeating background of beige paper with vintage look. Repeats to infinity, as usual.
Source V. Hartikainen
Remixed from a drawing in 'Maidenhood; or, the Verge of the Stream', Laura Jewry, 1876.
Source Firkin
Remixed from a drawing that was uploaded to Pixabay by ractapopulous
Source Firkin
Sort of like the Photoshop transparent background, but better!
Source Alex Parker
This texture looks like old leather. It should look great as a background on web pages.
Source V. Hartikainen
To get the tile this is based on select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
Like the name says, light and gray, with some small dots and circles.
Source Brenda Lay
A background tile for web with abstract repeating texture of dark "stone wall".
Source V. Hartikainen
A seamless pattern the unit cell for which can be had by selecting the rectangle in Inkscape and using shift+alt+i.
Source Firkin
Number 4 in a series of 5 beautiful patterns. Can be found in colors on the submitter’s website.
Source Janos Koos
Prismatic Groovy Concentric Background 5
Source GDJ
This makes me wanna shoot some pool! Sweet green pool table pattern.
Source Caveman
Light and tiny, just the way you like it.
Source Rohit Arun Rao
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
All good things come in threes, so I give you the third in my little concrete wall series.
Source Atle Mo
Colour version of the original seamless pattern.
Source Firkin
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
From a drawing in 'Hubert Montreuil, or the Huguenot and the Dragoon', Francisca Ouvry, 1873.
Source Firkin
Light gray version of the Binding pattern that looks a bit like fabric.
Source Newbury
Cubes as far as your eyes can see. You know, because they tile.
Source Jan Meeus
A seamlessly tile-able grunge background image.
Source V. Hartikainen
Number five from the same submitter, makes my job easy.
Source Dima Shiper
If you like it a bit trippy, this wave pattern might be for you.
Source Ian Soper
Seamless Prismatic Pythagorean Line Art Pattern No Background. A seamless pattern that includes the original tile (go to Objects / Pattern / Pattern To Objects in Inkscape's menu to extract it).
Source GDJ