Are you talking greenies or calico bags? I reuse the calico bags for household storage tasks, eg hubby has things in them hanging in the shed. I have some other non-green greenies that are being used for things like - toy bag for toys in the back of the car, keeping the picnic rugs in so I can just grab and go.

Your local op shop would probably be very happy to take any extras off your hands, they often reuse plastic shopping bags for their sales, so they would welcome any extra eco bags too.