Described herein are new methods for making lung bud organoids (LBOs) that have the capacity of developing into branching airways and alveolar structures that a least partially recapitulate human lung development from mammalian, preferably human, pluripotent stem cells including embryonic stem cells (ESCs) and induced pluripotent stem cells (IPSC), either by culturing branched LBO in a 3D matrix or by transplanting the LBO under the kidney capsule of immune deficient mice. Branched LBOs contain pulmonary endoderm and mesoderm compatible with pulmonary mesenchyme, and undergo branching morphogenesis. Also described are LBOs harboring certain mutations that induce a fibrotic phenotype, and methods of making same. The mutated (B)LBOs can be used for screening agents that may treat pulmonary fibrosis.