LaTiO3 films on SrTiO3 single crystal substrates exhibit metallic behavior attributed to the LaTiO3 film, the interface as well as part of the SrTiO3. In the limit of ultrathin LaTiO3 films on SrTiO3, the contribution to the metallicity from strain-induced electronic structure modification of the LaTiO3 film is minimized so that the dominant contribution to metallicity is from the interface and part of the SrTiO3 due to charge transfer of 3d electrons from LaTiO3 to SrTiO3. In such a limit, we observe quantum oscillations whose angular dependence indicates a three-dimensional Fermi surface. Such angular dependence is observed in two sets of quantum oscillations - one low frequency and one high frequency - that we have attributed to an inner and outer Fermi surface associated with a Rashba-like spin split hybridized dxz+yz band. © 2019 American Physical Society.