Eschscholzia californica was first collected at San Francisco in 1816 (Beidelman 2006, p. 51.). The taxon was established in Horae Physicae Berolinenses 74–75, pl. 15. 1820, Edited by Christianus Godof. Nees von Esenbeck.
The attached image is a jepg converted from the pdf illustration that is part of the protologue: the painting is credited to Fredrich Guimpel by Beidelmann (2006). The type specimen was collected by
Adalbertus de Chamisso (also known as Ludolf Karl Adelbert von Chamisso, 1781-1838) and Johann Friedrich Eschscholtz (1983-1831).
The attribution in the protologue reads: Habitat in arenis sterilibis siccs ad portum Sancti Francisci Californiae. Nunc, semine adlato, in hortis nostris, favente coelo, hospitabitus,
which I roughly translate to
Lives in dry, sterile sand at the port of St. Francisco of California. Now, from seed, grown in our gardens, the darling of heaven, very hospitable.
The holotype is ought to reside in the herbarium of the V. L. Komarov Botanical Institute, Saint Petersburg, Russia (LE). The herbarium website does not show a types catalog as of this writing. A related page “http://www.botguide.spb.ru/eng/herbarium_collections13.html” exhibits two thumb-nails images of Chamisso specimens. At some point, hopefully, an image of the actual holotype may become posted. In the meantime, the image serves as a proxy for the type.