Genealogy
To the best of my knowledge, the name Psinas (Ψήνας) can be traced back to the Greece province of Epirus, where a city was named after an Ioannina villager who owned land there. The city Psina still exists today, although many of the originating families have since migrated all over the world taking the name with them.
Psinas and Psina are the same word, the difference in the ending comes from the conjugation of the noun. The name appears to derive from an insect referred to as a "psin" in ancient Greek texts, which was involved in the reproduction of either Oak and/or Fig trees.
The pronunciation [psee-nahs] was changed to [sahy-nuhs] by some of those having migrated to America, presumably due to its foul similarity with another English word.