While writing the previous blog post about the Red Scarf Project, I needed to find an answer to the question - what is the plural of scarf? Is it scarfs or scarves?
The answer is both are correct. Scarfs was predominantly used prior to the 20th century and scarves is the current preferred usage. However, both spellings can be found throughout the 19th and 20th centuries and this really cool Google books n-gram shows that in English (both American and British) the switch from scarfs to scarves began to occur around 1930.
I'll stay with the current trend and use scarves but it's nice to know that I wouldn't have been wrong with scarfs. Probably the only wrong answer would be to mix the two spellings in the same post!
Source:Grammarist