At ds's preschool most of the kids did bring in toys. Other items were things they found outside...a leaf, acorns, special rocks, a frog. Some brought their pets which was always a big hit.
As the teacher said anythng will do. I think it is just to get them comfortable with talking infront of people, asking questions and answering questions. At ds preschool the children would get their show and tell item out of the box...(they would put it in a box at the start of school) He would stand up and tell a little about the item,(sometimes they would have nothing to say) the children then got to ask questions...what is its name...where did you get it...how does it work. When their turn was over they put the item in their mailbox...they were not allowed to play with the toys so there was no chance of it getting lost or broken.
I dont think bringing toys is silly...there isnt much else to bring and it gives him a chance to show and tell his friends about something he loves playing with. Before the class started the kids at ds school would be so excited to see what the others brought, they would ask if they could hold or try their toy...it was always calm and everyone was willing to share and show off their stuff. When class started, the teacher would say "carpet time everyone"...the kids would put their toys in the box and sit down on the carpet to start the day.