Grandma is a big fan of the deep box, hiding things in the popcorn (or beans or rice or sand) so you have to find them by feel. Our rice box at home is not deep enough to do this.
Every sensory bin, in my opinion, needs a few cups or scoopers to really experience the kernels. Here Starboy is using a dump truck, but we also have used: teacups from the play kitchen, measuring cups, small wooden bowls from Cost Plus World Market, scoopers from laundry soap, spoons, shot glasses, appetizer cups from Ikea, small Tupperware-style containers, plastic boxes from the Container Store, and more.
The Superstar Genius of Sensory Bins, though, is the brilliant school-at-home mom Mari-Ann of Counting Coconuts. She offers a different-themed bin every month. I tried this with Starboy and Mary Jane last fall, with what I considered to be limited success. Both kids found the number of objects in the bin overwhelming (over-exhuberance at the craft store on Mommy's part), which is fixable. Mary Jane LOVED her bin and played with it for months. Starboy pretty much cleared most of the Autumn stuff out of it then played cars in his as always. So I might try again. Stay tuned.