am looking for something to plant that comes up every year to twine around my mailbox;would get full sun.
thanks, I am in Northern Indiana.
It depends partly on how much you want to care for it; everything that's coming to mind tends to be something that will grow taller than a mailbox. Do you want foliage or flowers? My mom has an autumn-flowering clematis on her mailbox (in Lafayette, IN). It takes light pruning during the summer and a harder pruning in late fall to keep it from getting out of bounds, but it's not a lot of trouble. It attracts a lot of insects although that hasn't caused any problems for her or her mail carrier. I've seen other (spring and summer blooming) clematis on mailboxes, too -- although I know some of them can get large, I would imagine it wouldn't be too much work to keep them to size. Be careful with fall/winter pruning to not cut back too much; depending on the type you have, some bloom on old wood, and some bloom on new.
A climbing rose might work, and there are some roses that aren't technically climbers that could be trained on a mailbox (I'm thinking of some of the shrub roses and some of the single-flowered ones). They wouldn't exactly twine but would look charming. If you go that route, look for one with natural disease resistance for low maintenance, and I'd pick one that doesn't require covering in the winter (there are quite a few that fit both categories). I had a couple on my fence in IN that were lovely little bloomers -- a single yellow and a pink one (Fairy?) that had clusters of small pink blooms.
If you don't care about flowers, you could try English ivy (although I hesitate to recommend it, because it can be a thug). It would require some pruning a couple of times a season but it does have nice foliage, and there are some pretty variegated ones. I believe some of the latter don't grow so aggressively, either.
Trumpet vine would be a monster -- it's deceptive because it doesn't grow much the first 3-5 years but then it gets huge, and it would take over the surrounding area with shoots coming up everywhere -- so avoid that one! :) Honeysuckles and wisteria are also going to be too aggressive to work well there.
I know you asked for perennials but most will only bloom part of the season -- if you want prolonged bloom, you might look at annuals like morning glory or thunbergia.
I'm stumped for more ideas! I'm sure others will come up with some. Good luck!
Sweet autumn clematis is a stunning vine, but not a good choice for a mail box - bees swarm all over the flowers! Your mail person might not appreciate swatting stinging insects, and lots of folks (like me) are deathly allergic to bee venom, so I'd think carefully about planting this vine in the area of a mail box.
My mailbox has Clematis "Ramona" growing on it. It doesn't get much taller than the mailbox post. It has large flush of blooms in early June then blooms off and on during the summer and has another smaller flush of bloom in fall.
I cut this clematis completely to the ground at the end of the season and support it with a narrow trellis next to the mailbox post.
It is a work horse!