That was my DS. At that age he mainly played with role playing toys and things he could explore or pretend to be a grown up with.
His workman tools; tool belt, hammer, drills, screwdriver, construction hat, bits etc. not sure where you are but toysrus has a homedepot range for kids, makes the noises and sounds with batteries of course, he loved his tools.
His play kitchen with all the utensils and plates and pots etc. He also loved his toy BBQ
His sand/water table
His trucks and cars especially loving dump trucks and diggers and things that he could operate or work.
Little People farm set again
Home made stuff that he would sit for a good half hour with and bring out on his own. My Mum made it, she called it her
Junk Basket and filled a big peach basket so he could bring it around to a room and sit and explore all the goodies inside. The goodies included: old big screws, old remote control, old mobile phone, calculator, string, tape, washers, clips from dog leashes, old guts of a remote control, old but clean plastic pill bottles with lids, a maraca (from a trip to Mexico lol) a wood mortar and pestle, metal coffee filter, small screwdriver and wrench etc. just junk, things he could just explore by looking and touching and put "things together" build.