Food is a funny thing. It feeds and nourishes us, but it can also harm us. If I prepared the food and set some aside for myself, I would eat it. If the food was plated for a banquet and never served to a customer, I would eat it. If that same food was served to a customer and looked like it had not been touched, I would not eat it. I would never eat anything that had been served no matter how much I thought it was still edible.

Food can harbor unseen pathogens. Once food has been served, it should be considered contaminated and unsafe for anyone to eat except for the person it was served to. Unless you personally watched that plate go untouched the whole time and you never looked away, that plate should be considered unsafe for you to eat it.

I would imagine that the simple way is to emulate the paper envelopes of commercial seed packages. I believe the key to seed storage is to keep the seeds dry. A paper envelope will allow excess moisture to escape and also allow some moisture from the ambient air to enter.

You can buy paper envelopes or you can make your own with copy/printer paper and a bit of tape or glue.