The way to help you tell what it is before it flowers is to dig some up and look at the roots. Daylilies don't have a bulb - they have roots that usually have these little tuberous expansions on them. I don't know the correct terminology, but here are some pictures:
Those images are from these websites:
Wild Daylilies
The beautiful edible daylily
Of course, please don't consider eating them until they flower and you are positive on the identification! There are a few highly poisonous members of the lily family, so it's good to be very careful with that group of plants.
When I do eat them, though, my favorite part is the flower. They are tasty and pretty in food.