rations and pay for soldiers, dried rice
饟 centers on provisions for soldiers: rations and pay, and by extension dried rice as a preserved foodstuff suitable for military supply.
饟 combines 飠 (food) with 襄, which likely contributes the sound and possibly the idea of assistance or supply. The character is associated with providing food and pay to soldiers.
The food radical 飠 on the left suggests provisions, and the right side 襄 looks like a complex bundle. Imagine a soldier receiving a bundle of dried rice and pay: 饟 is military rations.
For ショウ, picture a soldier showing his rations: show -> ショウ, and the dried rice is displayed as proof of supply.