It depends on what kind of “lilies” they are.
If they look like this and this–with the flowers on the end of long, naked, flexible, rather sagging stems rising out of 12" high clumps of long narrow floppy green leaves–then they’re daylilies. Daylilies aren’t really “lilies”, and don’t grow from bulbs (they grow from rhizomes), but some of the more exciting daylily colors (besides the standard “orange” and “yellow” and “orange with dark red”) are considered fairly interesting by Gardening Persons. But if they’re just “orange”, then they’re almost certainly the very standard, very boring common daylily, the same plant that grows along roadsides all over the U.S., and only someone who’s looking for free ground cover to deal with an eroding bank will be interested in them.
If they look like this this or this–a bunch of tall stiff stems with small leaves all the way up the stems, with flowers at the tip of the stem–then they’re “lily” lilies. Orange lilies, while frequently lumped together colloquially as “tiger lilies”, can actually be any one of a number of separate species. And yes, Gardening Persons would be interested in them if they’re “lily” lilies.
If they’re daylilies, and someone wants them, the best time to dig them up will be starting in the spring, when the soil warms up enough so that their roots can have a decent chance of repairing the damage done by spading. I’d wait till April, for NC. And you can actually dig and transplant daylilies any time during the summer, as long as you make sure they’re kept watered and it’s not the middle of an atrocious heat wave.
If they’re “lily” lilies, they’re trickier to transplant, since the bulbs never really go dormant the way tulip and daffodil bulbs do, and you’d be better off letting the person who wants them come and dig them. That way it’s not your fault if they die after being transplanted. Usually lilies are dug in the fall after the top growth has died down, like October/November.
If you an ad in the paper that says, “Free lily bulbs. Orange”, the Gardening Person who responds is going to expect “lily” lilies, and will be mighty P.O.'ed to drive all the way across town to find plain old orange daylilies that you can find growing along roadsides all over the U.S. So find out what you’ve got first.