  Our primary objective is the formulation of a plausible cosmological
inflationary model entirely in terms of a pure modified gravity without any a
priori matter couplings within the formalism of non-Riemannian spacetime volume
elements. The non-Riemannian volume elements dynamically create in the physical
Einstein frame a canonical scalar matter field and produce a non-trivial
inflationary scalar potential with a large flat region and a low-lying stable
minimum corresponding to the late universe stage. This dynamically generated
inflationary potential is a substantial generalization of the classic
Starobinsky potential. Our model predicts scalar power spectral index and
tensor to scalar ratio in accordance with the available observational data.
