Stasher-brand reusable silicone bags
I LOVE Stasher-brand reusable silicone bags! They are easy to clean and close, they stay closed, and they come in many shapes, sizes and colors. They have enabled me to cut my previously embarrassing levels of disposable ziploc bag use enormously. I have tried many other (cheaper) brands, and this is the brand I prefer 100% of the time. They are BPA-free, leak free, and dishwasher safe.
You get what you pay for. They aren't cheap, but they are worth it. And, they even now have a line of Eric Carle bags for the little ones!
Click here for information and to order. The price below is for a pair of small "pocket" bags (snack sized, fits in your pocket), and prices go up from there.