You will want to collect things that have different tastes: salty (salt), sour (lemon), sweet (candy), bitter (cocoa powder - the unsweetened kind). My personal favorite when teaching "taste" is bitter. The kids see the cocoa powder and think, "chocolate!!!" However, their taste buds get something very different than what they are expecting. You can also talk about what animals eat (mice eat cheese, cats drink milk, etc) within this category.
Because I use this box at work, I've focused on things that move. This will hit upon the use or function of objects, which is another way to describe. Although it's not one of the 5 senses, kids like to move around and so it's something they can relate to easily. I've chosen 3 items: wind up toy (that actually goes in circles), car, and ball. You can talk about it's action (flying, driving, rolling, bouncing, throwing, catching, etc). You can describe the direction (forward, backward, up, down, around). You can even talk about where you see these objects (on the golf course, in the air, on the street). Get creative when talking about how things move!