Don't know what your soil type or moisture level is, but you'd probably want to look into "woodland" type flowers. If you're into native plants, then consider columbine, wild geranium, jacob's ladder, or foamflower. Maybe a chartreuse hosta and some impatiens would brighten the area, too.

the only thing I've ever seen to take the acidic soil and ultra-shady conditions under a pine are lily of the valley- and the pips aren't cheap, if you're buying them retail...

but they're a no-brainer to pull out of an existing clump, if you know someone who has them...

I laid some extra soil over the 'scratch between the roots' prep work I did, layed the runners out, spread dirt over them, mulched over the dirt, and kept them watered for the first month- it seems to have worked out ok.

Don't know how some of these grow in your area, but they do great in mine.

Rhody's, azaleas, hosta, skimmia's, many groundcovers, hydrangeas, foxgloves, woodland plants, and all listed above as well. I suppose a lot of what you want depends on how low the branches are.

Just remember if the tree is good sized your plants may require more water.

Well, other than the obvious (more pine trees), here in East Texas, the best thing that grows under pine trees, which we have an overabundance of, is poison ivy.

In all seriousness, if I were going to plant under a pine tree, I'd put some kind of border around (wood, stone, plastic, whatever) so I could make it into a raised bed and I'd add plenty of topsoil, mulch, planting soil. Anything that would get the acidity away from what I was going to plant.

Rod

Blueberry bushes. I have read on bush labels and in books that blueberry bushes love the acidic soil and shade. The green foilage is supposed to be attractive. Plant two different types for better pollenation.

I have 2 bushes to plant in my pine forest now.

I have also found a lot of incarnata passion flowers in my pine forest.

good luck
sam

A raised bed under the pine is likely to kill the tree eventually.

if you are looking for a pretty annual for under the pine tree I say impatients. Thats what Im gonna do this year with my pine.
~Kymmie

I have lily of the valley, hostas, daffs, wild violets, hellebores, and star of bethlehem bulbs. For annuals I waxy begonias, and lobelia planted.

Iris

I have planted under mine, rhododendron, orchid frost lamium, hosta, and a spreading ivy. I also let some of my house plants sit there in the summer.
Katbird

under my huge pine tree, ditch daylilies, sedum, hosta, purple coneflower, stella d'oro, iris....nearby, hollyhock, turtlehead, campanula, foxglove, dianthus, daisies.

if you are willing to mulch or add a litte improvement to the soil then just about anything that will take some shade/dry will do fine.