I'm a fiber artist and I work with exclusively plant (ok, sometimes insect) dyes!
I focus on getting a variety of yellows from local plants, with the occasional tan or pale green, and then adding variety with purchased dye stuffs like indigo and madder. If you're in the west Navajo Native Dyes -
https://www.google.com/books/edition/Navajo_Native_Dyes/yjEOAQAAIAAJ?hl=en&gbpv=0 is a classic written by a Diné master dyer in the 40s.
I made a bunch of sample skeins and cotton tea towels that were dyed with different yellow, then in indigo one way, and madder the other, giving a nice color wheel.
Not long ago I took a class on Mycopygments so now I'm often grabbing non-edible mushrooms and chucking them in a pot to play with. Since I often sell my yarns I can't use them for big projects unless I know it'll be colorfast.