Thompson’s Sandwort (Eremogone franklinii var. thompsonii)
Franklin’s Sandwort (Eremogone franklinii (Douglas ex Hooker) R. L. Hartman & Rabeler) (see photo) is a quite widespread cushion-forming plant species that occurs in the western USA.
The variety discussed here, however, is known only from the type that was collected in the 1930s somewhere in Gilliam County in Oregon, USA. It may be extinct, however, it was found once in the 1980s in Benson County, Washington so may in fact be still existing.
The La Brea Stork was described in 1910, originally based on fossil bones that were recovered from the rich La Brea Tar Pits in California, USA; however, the species was for more widespread and is now known to also have occurred in other parts of what today is the USA.
The species already appears in Late Pliocene deposits and disappeared at the end of the Pleistocene, but the population that inhabited the island of Cuba apparently survived well into the Holocene era and may even have been eradicated by the first human settlers.
Douglas’ Thistle Milkvetch (Astragalus kentrophyta var. douglasii)
The Thistle Milkvetch is a very thistle-like member of the legume family, the species includes around seven varieties which are distributed over a wide range of the southern USA.
The variety discussed here was described in 1964, it was restricted to a small area on the Colombia River at the boundery of Umatilla County in Oregon and Walla Walla County in Washington, USA.
Douglas’ Thistle Milkvetch hasn’t been collected since 1883, its habitat having been destroyed by dam projects and the plant is now considered extinct.
The photo below shows another variety, probably the nominate form.
References:  Astragalus kentrophyta Gray var. douglasii Barneby. Field Guide to Selected Rare Vascular Plants of Washington. Washington Natural Heritage Program and U.S.D.I. Bureau of Land Management 2005
The species appears to have been quite widespread, it was originally found in at least three sites: Amador Creek, Dry Creek, Grass Valley Creek, and Jackson Creek in the Amador County, but was also found in other areas including Alameda County, El Dorado County, Marin County, Mariposa County, and Shasta County in California, Benton County, Josephine County, Lincoln County, and Union County in Oregon, as well as Grays Harbor County in Washington.
The youngest specimens date to 1977, younger collections are not known, and it is possible that this species is already extinct.
Franklin’s Bumblebee is, or perhaps was, one of the most narrowly distributed bumblebee species of the world, it is known only from a small area between the coast and the Sierra-Cascade Mountains in northern California and southern Oregon, USA.
The species was last seen in 2006 at Mt. Ashland in Oregon and is now most likely extinct.
This species was described in 1951; it is only known from the type location: Rouge River National Forest in Jackson County, Oregon, USA.
“Length 5 mm. Color dark brown, slightly lighter on legs and venter.” 
The species seems to have never been recorded since its description and is thought to be likely extinct.
 Herbert H. Ross: Phylogeny and biogeography of the caddisflies of the genera Agapetus and Electragapetus (Trichoptera: Rhyacophilidae). Journal of the Washington Academy of Sciences 41(11): 347-356. 1951
This species was described in 1953 on the basis of a specimen that had been collected in 1948 at the foot of the western slope of Sexton Mountain in northwestern Josephine County, Oregon, USA. 
The Sexton Mountain Mariposa Lily was never again since and is considered extinct now, it is thought to have vanished due to the construction of the Interstate 5, the main Interstate Highway on the west coast of the USA.
 Morton E. Peck: A new Calochortus from Oregon: Leaflets of Western Botany 7(2): 190-192. 1954