The Panama-Pacific Exposition was held for almost the entire year of 1915 in San Francisco, California, USA. It celebrated the opening of the Panama canal and the 400-year anniversary for the discovery of the Pacific Ocean. It also celebrated the rebuilding of San Francisco after the earthquake and fires in 1906.
A number of different commemorative tokens, coins and so-called dollars were struck by different mints to honor the celebrations. The amazing website on so-called dollars called (what else?) So-CalledDollars.com tells us that this variety, with the Oregon state building, has the microscopic text 'W. & H Co. Newark. N.J' at the bottom of the obverse, just below the word 'FRANCISCO'. This W. & H. Co is 'WHITEHEAD & HOAG COMPANY' - an interesting old company. You can read more about their history on this website.
As far as values go, these coins (medals, really) are not often seen at auction. When they are, they seem to generally be in great condition as they are discovered at the bottom of grandparents' old boxes in dusty attics, never having been circulated. One coin is currently being sold by ATGCoins for $55 US dollars. It is slabbed by NGC and in fully uncirculated condition. If you had a coin in this condition, a collector might pay around this much. If you sold your so called dollar to a dealer, he or she would pay about half as much. The mark-up is necessary to keep the dealership solvent. CoinQuest thanks ATG for use of their coin photo.