Yes; you're both right.
In Bohemia, a part of the Holy Roman Empire then controlled by the Jagellonian monarchs, a guldiner was minted ... that was named the Joachimsthaler from the silver mined by the Counts of Schlick at a rich source near Joachimsthal (St. Joachim's Valley, Jáchymov) (now in the Czech Republic) where Thal (Tal) means "valley" in German. Joachim, the father of the Virgin Mary, was portrayed on the coin. Similar coins began to be minted in neighboring valleys rich in silver deposits, each named after the particular 'thal' or valley from which the silver was extracted. There were soon so many of them that these silver coins began to be known more widely as 'thaler'. From these earliest 'thalaer' developed the new Thaler – the coin that Europe had been looking for to create a standard for commerce.
http://en.wikipedia.org/wiki/Daalder
As silver flooded into the European economy from domestic and overseas sources, Thalers and Thaler-sized coins were minted all over with equivalent coins such as the crown, daalder from which the English word "dollar" is derived, krona, and from 1497, the Spanish 8 reales piece was minted - a coin which would later become known in some parts of the world as the peso. Indeed, in England the word "dollar" was in use for the Thaler for 200 years before the issue of the United States dollar,
As this Spanish 8 reale coin (left), more commonly called Piece of Eight (8 bits), was popular at our nation's beginning it became the basis of our silver dollar, sharing the same size & weight. The first coinage Act (1792) states:
DOLLARS OR UNITS--each to be of the value of a Spanish milled dollar as the same is now current, and to contain three hundred and seventy-one grains and four sixteenth parts of a grain of pure, or four hundred and sixteen grains of standard silver.
http://www.constitution.org/uslaw/coinage1792.txt