What does it mean to build with care, using what others leave behind? This question shapes the work of the Matter Matters Lab, an initiative founded by architect and researcher Catherine Söderberg Esper during the isolation of the pandemic. Drawing from experiences across cultures and motivated by a personal transformation during motherhood, Catherine began to investigate everyday waste as raw material for regenerative construction systems. Her first experiment involved gluing her own cut hair using white glue, initiating a radically intimate and handmade approach. Since then, the lab has focused on transforming organic waste into low-impact architectural materials, inspired by Indigenous knowledge systems and aiming to break from extractive models in construction. Projects like the Avocado Bricks, made from discarded avocado seeds, exemplify this approach of local, circular, and rooted in the idea of reciprocity between matter, place, and care, offering a new way of building with waste.