I love cloth bulk bags! Why? Because you can use them for so many applications! And when you're trying to avoid trash and plastic (especially around food) they are super handy dandy!
Here are just two of the most common and useful ways I use them and even where you can get yourself some too!
At the grocery store
I have at least 15 of these bags in a range of sizes and materials (some handmade and some store bought). I use them for bringing home fruits and veggies instead of the plastic bags they give out in the grocery store. I also use it for bulk food items in bulk bins. Everything from grains to dried beans, fruit, and sweets!
Weighing your bag
In order not to pay for the weight of the bag when you check out, you'll need to have the weight of the bag (the tare) written or committed to memory. If your bag doesn't have a tare weight on it, bring the empty bag to the service desk of any grocery store and have them weight out the bag. Once you know the weight of the bag you can now tell the cashier so she can subtract that amount from the bulk goods inside.
A note on plastic produce bags
I know many people like to reuse the plastic produce bags in the grocery store, and while I think that's fine, just remember that many single-use plastics like produce bags were only designed to be used once. We have to remember that plastics are made with petroleum and other (often undisclosed) additives and chemicals. Plastics tend to slowly photo-degrade around light and heat making them a bit unstable and constantly breaking down. Not something you necessarily want around your food or drink or in the environment. Plastic isn't digested by the planet, so avoid it in single-use applications as much as you can. Plastics are not evil, we just greatly misuse the material.
Whether I'm hitting up a local bakery, bulk bin for chocolate or a fruit stand, I always have some kind of small cloth produce bag with me to tote it home in! I especially love having one or two of these small bags while I'm traveling for the same reasons. I have even put a leftover sandwich in one before.