You're not going to get a lot in teh way of *flowers* in that shade, but it should be possible to grow *plants*, some of which will flower a bit.
I have two large (probably 20 yr old) Austrian pines in the front yard. They've been limbed up to where you can walk under them without having to duck too much. No supplemental watering whatsoever (except for newly planted things).
The ground under the one next to the driveway gets early morning sun and then from about 3 pm onward in the middle of summer: things that do well there include Lamium (deadnettle), perennial yellow foxglove, lemon balm, and lily of the valley. Also some shade-tolerant spring bulbs.
The ground under the other one (a wider, lower-limbed tree) only gets a bit of late-afternoon sun, although since the branches are not to the ground they get some general ambient 'open shade' type light all day. Things that do well there include sweet woodruff, astrantia, sweet cicely, Filipendula rubra, crested gentian, and solomon's seal.
If your site is windy, or is drier than mine, you might not be able to grow *all* of these, but the Lamium and sweet woodruff should be a good bet (if the lamium starts looking straggly in august, cut the bad parts back and it will come back better-looking in a few weeks), also solomon's seal if you want something taller. I am quite sure there are other things that would do well too, these are just the things I've planted myself.
Do not dig under the pine except to the extent it is absolutely unavoidable. For planting an area, your best bet is to strip off just the topmost layer of turf (if any) or remove whatever pavers are there, then set the plants into just very small shallow depressions and mulch around them with about 2-3" of some fine compost-y kind of mulch. Water regularly BUT NOT TOO FREQUENTLY for the first couple months. The idea is to encourage the plants to be thirsty enough that they send their roots DOWN into the native soil, but not so thirsty they actually croak
I would like to point out however that you still have to weed groundcovers. CERTAINLY for the first some years, and frankly there are hardly any that ever get so dense that you *never* have to weed them (pachysandra is the main one that comes to mind). (You could *try* pachysandra under there, I suppose). Of the ones I've mentioned, sweet woodruff comes the closest to suffocating out weeds, but even that you will have to weed for a while, and grass runners that get into it are *very* hard to remove effectively because the sweet woodruff itself is so dense.
Good luck, have fun,
Pat
