Answer: If the bulbs are tulips, hyacinths, or crocus, I'd toss them out and make another try next fall. Daffodils or lilies might still have enough in them to survive, if not flower this spring.
You can also plant them in spring, just to see what happens. Consider it an experiment. If they grow and flower, great. If they grow but don't flower, you might chose to leave them and see if they'll flower the following spring. Most likely they'll neither grow nor flower in which case they'll simply disappear into the soil.
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