Since I'm a gardener and plant collector rather than a bulb collector, per sae, bulbs have to fit into a broader scheme for the garden. Groundcovers function as a carpet to hold the garden/plant collection together in an attempt to make it look like a garden rather than a collection. On the subject of covering Colchicums, Acaena microphylla seems to function very well. It tends to die back a bit in the spring from crowding from the Colchicum foliage, but it returns with vigor after the foliage dies back. Acaenas have the annoying characteristic of spreading far and wide, though I have not (yet) been sorry I planted them. They seem to thrive in sun or light shade and thrive despite occasional dry soil. I've planted Vinca minor varieties as a floor for various parts of the garden. I am rather sorry to have planted it due to its rampant nature. Still, it covers Hyacinthella (Endymion or Scilla hispanica or whatever...) without much trouble to either. I use the California native strawberry, Fragaria californica, in the shady part of my front garden. While it appeared to be quite rambunctious the first season after planting, now, after 5 or 6 years it cohabitates well with Anomatheca laxa, Cyclamen coum and Cyclamen hederifolium, and Narcissus 'Thalia'. Another native, Whippleya modesta, a tiny relative of Philadelphus, seems to be loose enough to permit healthy bulb growth while competing with tree roots though it doesn't currently cover any bulbs. I have a "Hell Bed" outside the boundary fence which has several corms of Cyclamen trochopteranthum that are covered by Origanum microphyllum. They seem to cohabitate comfortably. The oregano is thin enough to permit the soil to dry out but is highly ornamental in the summer and fall. It self sows around a bit. I've always thought that a couple Midwestern natives, Oenothera macrocarpa (O. missouriensis) and Coreopsis verticillata selections would make excellent bulb companions since they start their growth later in the season. I've never tried them with bulbs, however. Brook Klehm Sebastopol, California, USA where we've barely gotten hot this season (so far...)