Pine forest rewilding.

I have an abandoned olive finca now full of pine.We have no water and we are on the edge of a baranc,the reason for it having been left for 30 years.
My question is ,what might be good to grow between the trees,no watering and poor soil not .withstanding.I have generated a small area for veggies.

Do you have an estimate for your average annual rainfall? If there is no water on site, my next thought would be what you can start from seed easily using the rain.

One thing that might be feasible to do is collect dried seeds from the plants that you find growing wild in your area, especially those that have edible or medicinal parts. These will be adapted to your conditions and have a much higher chance of surviving than just about anything else.

Gary,
Welcome to Permies! Hopefully people here will have some more ideas to help you. I think Jonah's idea is great - It will work whereever you are!
I'm guessing you are in a mediterranean climate from your description of the plot. I'm not sure what a baranc is - some sort of cliff or river bank? Obviously not a river bank though!
If you fill in your profile with a bit more information about your location and/or climate then this will help get more answers. Shade is good in a dry climate, but fire can be an issue in creating understories in some areas as you will no doubt be aware

Certain species of wildflowers & berries might be a good bet, but I have no idea what state you're in. Best assumption is California.

Also, work on diversity in your native pines & make sure they're not all the same one or two species. I've been looking into the matter in Ohio, since I have little to no idea of what an old growth pine forest should or would look like, & so far, we have four species of "true" pines, a species of spruce, something called a Tamarack & two species of Cedar- Eastern Red & Eastern White, plus a ground cover called Ground Hemlock. Good wildflowers/ berries to look for might be in the wood sorrel & wintergreen families, but I don't really know what else off the top of my head. As we said, give us a country/ state/ region & we might be able to help track down more specific info.

Gary, I love your idea.  And I like everyone's suggestions.

Not knowing how to recommend plants from your area, I would suggest looking for drought-resistant native plants.

Plants, even native plants will need two things:  Sun and water.

Seeds need water and sun to germinate.

If you are planting in a pine forest look for shade-loving native drought-resistant plants.

If you only rely on mother nature to do what she does there might not be as much success as a person would like.

Please consider helping mother nature out by proving the seeds or plants with some water to get them going the first year.