Chionodoxa Luciliea are closely related to Hyacinths and Scilla.  They bloom so early that they sometimes poke through the snow--hence the nickname "Glory of the Snow".  They are vigorous naturalizers and even spread by seed.  They can grow under trees or in sunny lawns like crocus.  Although similarly inexpensive, I think they give more "bang for the buck" than crocus.  Something everyone should try.

Zones 3-8.

Bulbs are naturally small at 4-5 cm, but are full blooming size.