Oak "forest" permaculture challenge

I would love to grow some edibles out on the back portion of our property.

The area has many oak and ash trees. (There are a couple of pear trees, I know not what species nor age, the fruit are very small and come ripe in August. They are too high for us, but we're very popular with the birds for a week!) Before we cut it, there was a ton of wild blackberry (but very sour), and poison oak. We're in a Zone 8 area. We have an average of 35 inches of rain a year, almost all November through February or occasionally March. Rain is rare in late spring through early fall, but we do have high groundwater. (This is the second year of a drought and the mowed weeds we call our lawn are green without watering.) In the "forest" there is often standing water for weeks on end, but again, it is when most of the trees are dormant. (At least none have drowned in the last two years we've been here.) Our first frost is in Early October and last in early May. Summers are very hot -- up to and beyond 100* often. Nights range in the 20*'s in the winter to the 50*'s in the summer. We have maybe a week of snow, all told. The area is mostly dappled shade. There are a couple of hot, sunny areas, but they are small.

I am looking for what kinds of edible understory plants I might be able to plant in such a challenging area. I would love to plant grapes, elderberry, currents and pawpaw, if there is a reasonable chance any would survive. (The person I spoke with from Raintree thought they would drown during our floods.) Medicinal and culinary herbs would be something I would like, too. The weeds LOVE it! We have dandelion and chicory, but I'd like to branch out!

Does anyone have any ideas for this microclimate from hell? I'd appreciate any encouragement.