Yellow
hop clover Trifolium agarium
spiny-leaved sow thistle Sonchus asper (a spiny sucker and the beauty of the plant is the strong curving of a leaf around the stem)
butter and eggs Linaria vulgaris
black medick Medicago lupulina
celandine Chelidonium majus
hawkweed Hieracium spp.
tall buttercup Ranunculus acris
dandelion Taraxacum officinale
moth mullein Verbascum blattoria
common mullein Verbascum thapsus

White
white sweet clover Melilotus alba
bladder campion Silene cucubalus
mouse-eared chickweed Cerastium vulgatum
oxeye daisy Chrysanthemum leuanthemum
field chamomile Anthemis arvensis
white clover Trifolium repens
jimsonweed Datura stramonium
black nightshade Solanum nigrum
Queen Anne's Lace Daucus carota
yarrow Achillea millefolium

Pink, Purple, Blue
red clover Trifolium pratense
Deptford pink Dianthus armeria
crown vetch Coronilla varia
chickory Cichorium intybus
teasel Dipsacus sylvestris
wild bergamot monarda fistulosa
bouncing Bet Saponaria officinalis
swamp milkweed Asclepias incarnata

Red, Orange
staghorn sumac Rhus typhina
bush honeysuckle Diervilla lonicera