A little bit early for me to tell what I'll have for digging, dividing, and sharing. I'll start listing things on the seed swap tool when I discover them as the garden is waking up, so keep watching for updates up to a few days before the get together. I'll also keep mentioning what I have on this thread.
As always, I have offshoots of my Lilac 'Palibin'. This is a small leafed Korean dwarf lilac that actually blooms reliably every year in our zone and smells heavenly. By dwarf, I mean dwarf in comparison to most lilacs. It still gets about 4 feet tall and wide (vs 8-10 feet), but other than the width spreading by offshoots that I don't pull, it has remained that height for many years. This has got to be one of my all time favorite shrubs.
I also have some tall bearded Iris 'Mary Frances' that has finally spread enough to share. This is a light purple. I got it in memory of my grandmother Mary Frances, so it has sentimental meaning for me.
For a crazy spreader, I can offer up Silene armeria (I think Robin is also offering this). This one does spread prolifically, but is a really charming plant if you have an area that you want to fill. It is fairly easy to pull, but be forewarned
Other crazy spreaders are the campanula. I have 'Elizabeth' that David and Pat have shared with many of us, and for the first time I have another campanula in a deeper shade of pink/mauve called 'Ringsabell Mulberry Rose'. Again, really charming plants but they do spread prolifically - I think they do all right in containers though if you want to keep them in bounds.
I also have a noid big root geranium. These grow into big clumps, easy to divide, but are not self spreaders like the silene and campanula.
I can dig up a few daffodils if there is interest. I have 'Yellow Cheerfulness', 'Thalia, 'Lemon Drops'.