I've also looked at the websites of US-based Catholic church supply shops, but then I see all the possibilities, not the most probable ones. Also, I think tradition may have changed between the 1960s and now (it has in my country).
So the question is: If a person went to Catholic Mass on Palm Sunday in New York in the 1960s (general Catholic tradition or maybe Italian American Catholic) and took the "palm branch" that was handed to him and brought it home without changing it in any way, what would it most likely have been? A green leafy thing or palm frond? Fresh and green or dried and brown? Already woven into a cross or not? A branch from some completely different plant?