Unknown country and mark on spoon

I’ve been going through some of my grandmother’s things and have come across a sterling spoon that I can’t identify. I’ve been through hallmark and pattern guides without finding an answer. I’d be so grateful if someone could either identify the hallmark, or point me in the right direction.

Use of the word “sterling” implies that it is almost certainly from the USA, but I can’t find that symbol in any of my usual look-up pages.

Phil

Thanks so much! I’m glad to know that it’s American. I’ll keep searching for the mark.