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
From a drawing in 'Art Embroidery', M.S. Lockwood and E. Glaister, 1878.
Source Firkin
A free seamless background pattern for use on websites.
Source V. Hartikainen
This was formed by distorting an image of a background on Pixabay.
Source Firkin
From a drawing in 'Cassell's Library of English Literature', Henry Morley, 1883.
Source Firkin
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
This is the remix of "plant pattern 02".I changed the object color to white and the BG to purple.The image a seamless pattern derived from a weed which I can't identify.The original weed image is from here:jp.pinterest.com/pin/500744052301423641/
Source Yamachem
Seamless , tileable CC-0 texture. Created by my own, feel free to use wherever you want!
Source Linolafett
Prismatic Hypnotic Pattern 2 No Background
Source GDJ
Prismatic Rounded Squares Grid 3 No Background
Source GDJ
A seamless pattern created from a square tile. To get the tile, select the rectangle in Inkscape and use shift+alt+i.
Source Firkin
One of the few full-color patterns here, but this one was just too good to pass up.
Source Alexey Usoltsev
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 4
Source GDJ
Continuing the geometric trend, here is one more.
Source Mike Warner
A pattern drawn in Paint.net and vectorized in Inkscape.
Source Firkin
Remixed from a drawing in 'Kulturgeschichte der Deutschen im Mittelalter' Franz von Loeher, 1891. The unit tile can be had by selecting the rectangle in Inkscape and using shift-alt-i
Source Firkin
Abstract Stars Geometric Pattern Prismatic No Background
Source GDJ
Scanned some rice paper and tiled it up for you. Enjoy.
Source Atle Mo
Used correctly, this could be nice. Used in a bad way, all hell will break loose.
Source Atle Mo
Prismatic Curved Diamond Pattern 6 No Background
Source GDJ
I scanned a paper coffee cup. You know, in case you need it.
Source Atle Mo
Prismatic Floral Background No Black
Source GDJ
Remixed from a drawing in 'Analecta Eboracensia', Thomas Widdrington, 1897.
Source Firkin
A seamless marble-like texture colored in light blue.
Source V. Hartikainen