Burlap coffee or potato bags for garden (lafayette / orinda / moraga)

Hi! I’m looking for free, used burlap coffee bags to use as mulch on a hillside.
I’m growing extra tomato plants for the Farmer to Kids summer food program and am trying to cultivate in some pretty challenging soil.
I find burlap bags work great to keep the soil covered, and I need another 12 bags to complete the row.
If you have any you can donate, I’d be very grateful 👌🏻