Flower Heads often look like fabric buttons or pincushions when viewed from above. The flowers usually appear rayless, and are usually all disk flowers:
or 
Pathfinder Adenocaulon bicolor:
Bursages and Burweeds: The Genus Ambrosia
Bur Ragweed, Annual Bursage, Annual Burweed: Ambrosia acanthicapra (Synonym: Franseria acanthicarpa)
Annual Ragweed, Common Ragweed: Ambrosia artemisiifolia (Synonyms: Ambrosia artemisiifolia var. elatior, Ambrosia artemisiifolia var. paniculata, Ambrosia elatior, Ambrosia glandulosa, Ambrosia monophylla)
Pearly Everlasting Anaphalis margaritacea:
Wildflowers of the Genus Antennaria: The Pussytoes
Low Pussy-toes Antennaria dimorpha
Woodrush Pussy-toesAntennaria luzuloides
Field Pussytoes Antennaria howellii ssp. neodioica (formerly A. neglecta var. attenuata)
Field Pussytoes Antennaria howellii ssp. howellii (formerly A. neglecta var. howellii)
Slender Pussytoes Antennaria racemosa
Rosy Pussy-toes Antennaria rosea (A. microphylla)
Narrow-leaf Pussytoes Antennaria stenophylla
Umber Pussytoes Antennaria umbrinella
Wildflowers of the Genus Arctium:
Great Burdock, Greater Burdock: Arctium lappa (Synonym: Lappa major)
Common Burdock, Lesser Burdock, Small Burdock: Arctium minus (Synonym: Lappa minor)
Wildflowers of the Genus Arnica:
Rayless Arnica, Rayless Leopardbane: Arnica discoidea (Synonyms: Arnica discoidea var. eradiata, Arnica grayi, Arnica parviflora, Arnica parviflora ssp. alata, Arnica parviflora ssp. parviflora)
Wildflowers of the Genus Artemisia: The Wormwoods and Sagebrush
Biennial Wormwood Artemisia biennis:
Northern Wormwood Artemisia campestris var. scouleriana:
Douglas' Wormwood Artemisia douglasiana:
Dragon Wormwood Artemisia dracunculus:
Riverbank Wormwood Artemisia lindleyana:
Western Wormwood Artemisia ludoviciana:
Suksdorf's Wormwood Artemisia suksdorfii:
Mountain Wormwood Artemisia tilesii:
Wildflowers of the Genus Bidens: The Beggar Ticks
Leafy Beggar Ticks Bidens frondosa:
Wildflowers of the Genus Cacaliopsis: Silvercrown
Silver Crown Luina Cacaliopsis nardosmia (formerly Luina nardosmia):
Wildflowers of the Genus Centaurea: Knapweeds
Bachelor's Button, Cornflower, Garden Cornflower: Centaurea cyanus
Diffuse Knapweed, Tumble Knapweed, White Knapweed: Centaurea diffusa
Spotted Knapweed: Centaurea stoebe ssp. micranthos (Synonyms: Centaurea biebersteinii, Centaurea maculosa)
St. Barnaby's Thistle, Yellow Star Thistle, Yellow Star-thistle: Centaurea solstitialis
Wildflowers of the Genus Chaenactis: The False Yarrows
Hoary False Yarrow Chaenactis douglasii : Upright wildflower with cottony, lacy pinnate leaves. Several to many white or pink-tinged disk flowers which look like pincushions. Plants to 1.5 feet tall.
Wildflowers of the Genus Cirsium: The Thistles
Canada Thistle Cirsium arvense
Mountain Thistle Cirsium callilepsis (C. centaureae)
Weak Thistle Cirsium remotifolium
Wavy-leaf Thistle Cirsium undulatum
Bull Thistle Cirsium vulgare
Wildflowers of the Genus Gnaphalium: The Cudweeds
Slender Cudweed: Pseudognaphalium canescens ssp. microcephalum (formerly Gnaphalium canescens ssp. thermale and formerly G. microcephalum var. thermale) -
Lowland Cudweed / Western Marsh Cudweed: Gnaphalium palustre -
Purplish Cudweed: Gamochaeta purpurea (formerly Gnaphalium purpureum) -
Cotton-batting Plant: Pseudognaphalium stramineum (formerly Gnaphalium stramineum or formerly G. chilense) -
Marsh Cudweed: Gnaphalium uliginosum -
Wildflowers of the Genus Grindelia: The Gumweeds
Columbia River Gumweed Grindelia nana var. discoidea (formerly G. columbiana ssp. columbiana): Erect plants with distinctive reflexed or out-curved bracts on the involucres. They may look like spiny green balls. The leaves are oblanceolate with entire margins or with sharp to blunt teeth on the margins. The involucres are noticeably resinous.
Wildflowers of the Genus Hymenopappus:
Low-tufted Hymenopappus Hymenopappus filifolius var. filifolius - Plant to two or three feet tall. Several stems arise from a woody base. Leaves tufted at the base, once or twice pinnatified. Flowers discoid, yellow in color, about the width of a nickel.
Wildflowers of the Genus Lasthenia:
Smooth Lasthenia Lasthenia glaberrima -
Wildflowers of the Genus Logfia (Filago):
Field Cotton-rose, Field Filago, Cudweed: Logfia arvensis (Synonyms: Filago arvensis, Oglifa arvensis)
Wildflowers of the Genus Matricaria: Pineapple Weed
Disc Mayweed, Pineapple Weed Matricaria discoidea (Synonyms: Chamomilla discoidea, Chamomilla suaveolens, Matricaria matricarioides, Santolina suaveolens) - Low plants with stiff, often branched stems. Leaves are fern-like, with thin segments. Disk is elevated, like a green thimble. Plants have a noticeable pineapple smell when the herbage is bruised or crushed. A common weed of fallow fields and yards.
Wildflowers of the Genus Onopordum: Cottonthistles
Cottonthistle, Cotton Thistle, Scotch Cottonthistle, Scotch Thistle, Scots Thistle: Onopordum acanthium (Synonym: Onopordum acanthium ssp. acanthium)
Wildflowers of the Genus Petasites: The Coltsfoots
Arctic Coltsfoot, Sweet Coltsfoot, Western Sweet Coltsfoot Petasites frigidus var. palmatus (Synonyms: Petasites palmatus, Petasites speciosus) -
Wildflowers of the Genus Psilocarphus: The Woolly Heads
Dwarf Woollyheads, Dwarf Woolly Heads, Short Woollyheads: Psilocarphus brevissimus var. brevissimus (Synonym: Psilocarphus globiferus) -
Meadow Woollyheads, Tall Woollyheads, Tall Woolly Heads: Psilocarphus elatior (Synonym: Psilocarphus oregonus var. elatior) -
Oregon Woollyheads: Psilocarphus oregonus -
Slender Woollyheads: Psilocarphus tenellus (Synonym: Psilocarphus tenellus var. tenellus) -
Wildflowers of the Genus Pyrrocoma: The Goldenweeds
Columbia Goldenweed, Large-flowered Goldenweed, Rayless Goldenweed: Pyrrocoma carthamoides var. carthamoides (Synonyms: Haplopappus carthamoides ssp. carthamoides, Haplopappus carthamoides ssp. rigidus, Haplopappus carthamoides var. carthamoides): Prostrate wildflower with one to several stems, large oblanceolate leaves, and wide flower heads surrounded by widely triangular bracts. Flowers yellow and entirely discoid.
Wildflowers of the Genus Senecio: The Butterweeds or Groundsels
Sweet Marsh Groundsel Senecio hydrophiloides (formerly S. foetidus var. foetidus)
Great Swamp Groundsel Senecio hydrophilus
Common Butterweed Senecio vulgaris
Wildflowers of the Genus Tanacetum:
Common Tansy Tanacetum vulgare: Erect stemmed plants with many fern or pinnatifid leaves. Flower heads many and yellow in flat-topped clusters. Individual flower heads look like flattened fabric buttons.
Wildflowers of the Genus Xanthium:
Common Cocklebur Xanthium strumarium :