We have family assembly on Friday, all parents are welcome and the children show certificates and awards they have earned both in school and outside-we get Blue Peter badges, letters from the Queen, karate certificates, cups from cart racing, the lot!!
I'd say that wanting to tell his friends is normal. Not sure about anything more than that. I'd be guided by the school culture, so if brownie/cub badges, sporting/musical awards get announced at assembley, then fair enough. My school reserved announcements for those who were getting capped for national teams and Oxbridge exhibitions.
Do you mean taking in a certificate from Cubs or Football or music lesson or something ? Depends on the school - many schools have a special 'Celebration Assembly' specifically for this purpose. It's lovely to hear of all the things dc get up to outside of school. If there isn't this culture in the school, then that would be different, I suppose, but I don't know well, any (Primary) schools that don't have some kind of forum for this sharing of good news.
If DD2 gets a certificate out of school I absolutely encourage her to take it in for show and tell, and also to show the HT. She finds all school hard: academic, art, sport. So a certificate showing she swam 1 mile is a massive thing for her.
At my DD's primary children were encouraged to take in swimming certificates, karate gradings, music exam results etc which were read out and the child went up to receive their certificate from the Head.
I wouldn't send it in if this wan't the norm though!