(please excuse weird words/spelling. I'm typing while singing my daughter to sleep)
A lot of the plants on my
Edible Plants for Shady &/or Wet Areas (especially in temperate climates like the Northwest) should work.
Some of fruiting plants might not fruit if planted close to the trunk/deep shade, but they will grow. Huckleberries should do well! I have some growing out of hemlock stumps, so if you have
enough woody debri underneath, they should do well. One thing that helps is to bring soil from where there's already hucklberries growing, in a nice big chunk, and plant that soil with the huckleberry. I've saved quite a few dying blue hucklberries by transplanting soil from around red hucklberries. I've also successfully transplanted hucklberries quite a few times by just digging up a big chunk of soil with it, and planting it all together. If you were closer, I'd give you some red huckleberry plants, as they grow wild on my property, just growing in the woody soil)
Rhodies work alright under douglas firs, especially under the sunnier side. Miners lettuce grows under it well, too. Skunk/swamp currant, and red flowering currant do well. You might try other currants and gooseberries. My mom had jostaberry that did fine getting dappled and morning sun. It was leggy, but it made berries.
I've got babbington leeks growing successfully on the outskirts of my firs, and I'd think that chives would do well, as well.
For flowers (I don't think any of these are edible). my mom planted helabor and coral bells under her douglas fir. Bleeding hearts, of course, also do well. Hostas should do well, as well (hostas are edible, too!).