These subtle botanical-dyed textiles by Loraine of Grijs were made, in order, from:
Red onion (middle and right swatches)
Logwood and iron (2nd and 3rd photos) – this was the closest she could get to a dark brown.
Oak gall and cutch – the top swatch is oak gall left standing for one night and pretreated with tannin, while the one below was not; the lower are cutch.
We wish vegetable-dyed fabrics like these were not so difficult to find.