The Sandbar Milkvetch is known exclusively from the type material that had been collected in 1947 near Cameron in Coconino County, Arizona, USA, where the plant grew a gravelly washes and sandbars of summer-dry streams at elevations of 1110-1200 m.
This species was never found again and is believed to be extinct.
The Phillip Island Glory Pea, aka. Flesh-colored Glory Pea, was endemic to Phillip Island in the Norfolk Islands; it is the sole member of its monotypic genus.
The species died out in the wild around 1830 due to introduced ungulates, however, it was kept in several botanical gardens for some time, however, all these cultivated plants seem to have subsequently disappeared as well.
The Pseudocylindric Milkvetch was described in 1915, the species was apparently endemic to a very small area in the valley of the Euphrates in the Kemaliye District, Erzincan Province in eastern Turkey. 
The species appears to have been restricted to habitats close to the Euphrates river and disappeared when the Keban Dam was built from 1966 to 1974, probably due to habitat loss by rising of the river’s water level. 
References:  Zöhre Bulut; Hasan Yilmaz: The current situation of threatened endemic flora in Turkey: Kemaliye (Erzincan) case. Pakistan Journal of Botany 42(2): 711-719. 2010  Munir Ozturk; Umit Kebapci; Salih Gucel; Esat Cetin E.; Ernaz Altundag: Biodiversity and land degradation in the lower Euphrates subregion of Turkey. Journal of Environmental Biology 33: 311-323. 2012
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
Rimbach’s Bean is a somewhat enigmatic species, that is known from the type collection which was collected at an elevation of about 2800 m near the city of Riobamba in the Chimborazo Province, Ecuador at an unknown date. [?]
The species was described in 1940, it was a up to 5 m tall climbing liana with the leaves having a conspicuously glaucous under surface.
Rimbach’s Bean was never found again since, the type locality is now more or less destructed, so the species is most probably extinct.
The King’s Wattle was described in 1928, it was endemic to Western Australia.
The species was a shrub of about 2 to 3 m height, like most of its kin it did not have leafes as a fuklly-grown plant but so-called phyllodes, leaf-shaped twigs, which in this species were about 0,1 cm long and 0,2 cm wide [which is a odd size in my opinion], and furthermore had yellow flowers.
The King’s Wattle is now most likely extinct.
Two additional wattle species, Acacia mathuataensis A. C. Sm. from Vanua Levu, Fiji and Acacia prismifolia E. Pritz. from Western Australia were formerly thought to be extinct as well, but were both rediscovered in 2015 and 2018 respectively.
Robbins’ Milkvetch (Astragalus robbinsii var. robbinsii)
Robbins’ Milkvetch was described in 1841, it includes around seven varieties which occur in northern North America, some have highly restricted ranges others are more common.
The nominate variety certainly was one of those with a rather restricted distributional area, it is known from limestone ledges on only a single site on the Winooski River in the town of Colchester in Chittenden County, Vermont, USA. This habitat was destroyed by the building of a dam in 1894, leading to the global extinction of this plant.
References:  Nathaniel Lord Britton; Addison Brown: An illustrated flora of the northern United States, Canada and the British possessions: from Newfoundland to the parallel of the southern boundary of Virginia, and from the Atlantic Ocean westward to the 102d meridian. New York: C. Scribner’s sons 1913
This is a somewhat enigmatic species which was actually described from cultivated plants kept in the garden of Hewett Cottrell Watson, the species’ author.
Some of these plants were also brought to the Royal Botanical Garden in Kew, Great Britain, but unfortunately all propagation efforts failed.
The Sao Miguel Vetch apparently was restricted to the island of São Miguel in the Azores, Portugal, where it was only ever recorded (sometimes between 1944 and 1949) from the Serra da Tronqueira. The only known population apparently was destroyed by a landslide, however, introduced grazing mammals may have played a much bigger role in its extinction.
The Hainan Ormosia is, or rather was, a 10 m tall tree endemic to the island of Hainan, China, that was found only two times, once in 1954 and a second time in 1957, both times in extremely small populations.
The species has not been found since and is very probably extinct now.
Parr’s Parkia was described in 1883, it is known only from the type collection that was allegedly made on the enigmatic ‘Parr’s Coffee Plantation’ somewhere along the Rewa River on the island of Viti Levu, Fiji, a locality that now cannot be traced anymore.
According the the information accompanying the type, however, it was also found on the island of Vanua Levu.
The species was described as being an about 21 m tall tree with a 12 m tall trunk, the finely divided leaves are said to be about 30 cm long with six to eight opposite pairs of 10 to 12,5 cm long pinnae, which again bear about 1,6 to 1,9 cm long opposite leaflets.
The Fijian name was said to be vaivai, which is a generic name given to many legume species with finely divided leaves. 
 Helen C. Fortune Hopkins: The Indo-Pacific species of Parkia (Leguminosae: Mimosoideae). Kew Bulletin 49(2): 181-234. 1994