Arbutus
The bark that naturally peels off the Arbutus is a source for brown dye and tannin.
Beets
Beetroots don't give a very colourfast dye but the leaves will produce yellows.
Bloodroot
Oranges, pinks, reds.
Burdock Root
Yellows with alum mordant.
Clematis
The leaves of clematis give yellow.
Coreopsis
The flowering heads of coreopsis are popular for yellow and orange dyes.
Dahlias
Dandelions
Dandelion roots are said to give a pink dye but I haven't been successful with this yet.
Hollyhocks
Hollyhocks produce shades of pinks and blues with different mordants.
Lady's Bedstraw
A dye source for pinks and reds.
Mountain Laurel
The mountain laurel can be used for grey dyes.
Purple Loosestrife
Purples, greens and black colours.
Red Alder
The bark of the red alder can give a red dye.
Russett Buffalo Berry
A source for red dye.
Strawberry Blite
Sweet Woodruff
Sweet Woodruff and White Bedstraw are of the same family as madder, so can give pink/red shades of colour.
Western Red Cedar
White Bedstraw
White Bedstraw is a source for red dye.
Yarrow
Yarrow flowers produce a yellow dye.