My copy came from the Oxfam Bookshop in Canterbury, £1.99. It's a 1964 Penguin paperback; I suspect it's now out-of-print, but the stories are probably available in other collections.
This is a collection of short stories that won Hugo awards between 1955 and 1961. I'd read most of the stories before, but I didn't previously own the book.
It's of interest to me mostly because it includes Eric Frank Russell's short story "Allamagoosa", which is where I got the word "offog" from. I won't spoil the story by explaining further.