Stasher Sandwich Bag | $10 | Amazon
This isn’t the only silicone food bag out there, but Stasher is unique in that it doesn’t use any plastic at all. Basically every other silicone bag requires you to slide a plastic bar across the top of the bag to seal it, but Stasher is entirely self sealing, with no extra pieces.
You can use it to carry sandwiches to work, to store leftovers, or my personal favorite: for sous-vide. $10 is an all-time low, and while that’s a lot of money to spend on a sandwich bag, just remember that it’s a sandwich bag that’ll last essentially forever.