In this bento: three hand shaped purple onigiri with slices of olive for eyes, a red pickled ginger mouth, and spaghetti antennae, a piece of steamed corn, steamed romano green beans from Crescent Moon Farms, cherry tomatoes with a CUTE leaf pick, and fried padron peppers also from Crescent Moon Farms. If you are wondering where to get purple sweet potatoes, I suggest checking your local asian market. I found the potato used in this bento in San Francisco's Nijiya Market, but today I discovered the same kind of purple sweet potatoes at the Asia Mart on Guerneville Road in Santa Rosa. They may also be called Hawaiian Okinawa Sweet Potatoes. They are white skinned with a deep purple flesh.
To make purple rice, simply mash some cooked purple sweet potato and them mix it into cooked rice. Shape it using a piece of plastic wrap covering your hand, so that it doesn't stick to your fingers.