Proto-Indo-European *dʰel- "curve, hollow" became German Tal "valley". A coin called the Joachimstaler (so called because it was made at a silver mine in Joachimstal "Joachim's valley"), was clipped to taler. This corresponds to Dutch and Low German daler, where it was borrowed into English as daler, daller then dollar.
German Tal, also spelled Thal, is also in Neanderthal, the valley where its bones were first discovered.
In English the PIE root became dell and dale.
In Greek it became θαλάμη thalamē "lurkingplace, den, lair", also "of cavities in the body", as in English thalamus, a word which has something to do with the brain, and also flowers.
Pokorny suggests that it is also found in ὀφθαλμός ophthalmos "eye" from a combination of ὤψ ōps "eye" and thalamē. Others disagree.