Cobbles, bricks, decorative stones wanted for school garden

Parents at Stroud Green Primary are involved in a project to build a small garden in the playground, including making a low wall from mesh boxes called gabions. We are aiming to fill them with as many locally sourced/ recycled items as possible. if anyone has any spare bricks, air bricks, cobbles, decorative rocks etc any items would be very gratefully received. We are also on the look out for a few sleepers. I live at the end of the ladder so can collect . Thank you