If you see crocus in flower arrangements in the spring, these are the ones being used. You can easily do this yourself. You might also search out some C. vernus bulbs. These are one of the late blooming forms and extend the season another week or so. They like a bit more water and slightly deeper planting than other crocus bulbs and are well worth the effort.
Some people complain that their crocus bulbs never last very long in the garden.
The major reason for this is that they are getting too much water during the summer. This bulb likes its summer soil dry and hot while its spring and fall garden area can be a tad damper. Never plant it in areas where you will grow summer annuals. If you water the annuals enough to get them to bloom well, you are giving the crocus too much water and shortening their life. The exception to this is C. vernus.