I thought Samhain and Beltane. I guess there’s some bias there… I’m also not American, and have never heard of St. Swithin’s Day (is it a popular thing?).
My psychic armor remains inviolable. First thing that came to mind was St. Valentine’s Day.
After that came to mind, I did a little bit of thinking to make sure that there wasn’t only one holiday with an ‘n’ in its name, and came up with Ramadan.
Sorry, you failed. I’m French and the first name that came to my mind was “Noel” (Christmas). Then I tried to remember the word “Thanksgiving”, but somehow I blanked out and was unable to conjure it up (It’s not “Turkey’s day”, it’s not “Dinner with the in laws day”, how the hell do they call it?)
St. Swithin’s Day isn’t quite as popular as Christmas, Thanksgiving, or Halloween but it is the 4th or 5th biggest American holiday slightly ahead of the 4th of July. I know it is mainly an American holiday but I am surprised you have never heard of it. I thought the elaborately costumed livestock pageants would have universal appeal.
I didn’t think of St. Swithin’s Day however. My first thought was: