I haven’t tried most of these, but have heard that they produce colour.

Strawberry Blight
Latin: Chenopodium capitatum

Low lying plant with leaves spaced far apart. Where the leaf joins the stem is a cluster of bright red fruit. Use the juice of the berries for a pink/purple. Try vinegar to set the dye, or an alum mordant.

Avocado
Scrub the peels clean. Add to bath of vinegar and cream of tartar. Rosey gold. Add premordanted wool (alum)
Also try avocado pits.

Avocado Pit Dye Vat
Dyeing with Avocado Peels and Pits

Purple Cabbage
Mordants:
Alum – yellow, beige
Ammonia – pale green
Tin – lavender
Vinegar – pink, lilac
Afterbath: add washing soda dissolved in boiling water
turquoise

Black Birch
Simmer birch bark in dye bath. Add mordanted wool. Simmer.
Colour: pinkish beige

Hollyhock berries
Colour: pale yellow.
(or sometimes blue!)

Hollyhock: Greenish side of Blue
Coreopsis Tinctoria

Use 1 1/2 cups of flowers per dye bath.
Mordants:
alum – antique pine
iron – dark brown
copper – chestnut brown
tin – gold
Delphinium Blossoms
Colour: sage green
Horseradish leaves

Geranium Leaves
Simmer with rusty nails or in an iron pot.
Colour: dark grey
Willow bark
Colour: Coffee cream Choke cherry

Colour: pink
Dyeing with Willow Bark

More Natural Dyes
Madder
Sandalwood
Osage Orange
Logwood
Cochineal

Natural Dye Books
Wild Color, Revised and Updated Edition: The Complete Guide to Making and Using Natural Dyes
Botanical Colour at your Fingertips
The Modern Natural Dyer: A Comprehensive Guide to Dyeing Silk, Wool, Linen and Cotton at Home
A Weaver’s Garden: Growing Plants for Natural Dyes and Fibers

The Rainbow Beneath My Feet: A Mushroom Dyer’s Field Guide
Harvesting Color: How to Find Plants and Make Natural Dyes
A Heritage of Colour: Natural Dyes Past and Present by Jenny Dean (2014-06-10)
Wild Color, Revised and Updated Edition: The Complete Guide to Making and Using Natural Dyes
The Art and Craft of Natural Dyeing: Traditional Recipes for Modern Use