This was a book of short sci-fi stories for boys. It was illustrated and probably aimed at somewhere like 6-9 year olds. I would have had this book in the 70s or 80s I think. In the UK.
The only story from it I remember concerned a boy who was beamed up from his bed and 'borrowed' in order to represent some aliens playing a ball game in zero gravity, against their enemies. The friendly race had identified him as being their saviour due to skills they'd observed from him on Earth. Obviously he wins, saves the day and then wakes up wondering whether it was all a dream. Then he finds an artefact by the bed which proves it definitely happened.. might have been a leather glove, baseball style.