  We shall study the formation of a particular class of regular black holes
from the gravitational collapse of a massive star. The inside geometry is
described by spatially flat Friedmann-Robertson-Walker metric and the stellar
matter is distributed uniformly without any pre-assumption about its equation
of state. Our model is a generalization of Oppenheimer-Snyder collapse for
regular black holes. We have obtained the density and pressure of star by
applying the condition of smooth joining of metrics at the freely falling
surface of star. Specifying the regular black holes to Hayward and Bardeen
cases, we see that the stellar matter is described by a polytropic equation of
state and moreover, for the radius smaller than a certain value, the strong
energy condition becomes invalid. Then for both black holes, the interior
apparent and event horizons and also the stellar surface are obtained as
functions of the proper time of star. At the end, we have constructed a new two
parametric family of regular black holes jointed smoothly to the flat
Friedmann-Robertson-Walker interior metric of a polytropic star with an
arbitrary index.
