Companion Plants to Sycamores????

I have a few questions for everyone.

I am currently working on two projects at my school, first were building a native garden of plants in Southern California. I was okay with just using coastal sage scrub and chaparral, however, the feeling is we want to add some Sycamores as well. Are there any suggestions of native plants that grow well under or around Sycamore trees? This project is taking place at Whittier College, and the soil we will be working with is primarily clay, and nutrient poor.

On an adjacent plot of land we are attempting to design a food forest. I have some ideas--we want the forest to be fully functional and drought tolerant. However, I am looking to see if anyone has any suggestions. Please let me know.

Thanks,
Duncan

We see Sycamores often on hikes near the river and creeks around here, so I will take a look soon to try to identify what is growing in the immediate proximity. Obviously, wetland and riparian plants. I know that we see lots of Spicebush, PawPaw, American Beech, Virginia Creeper, horse nettle, Christmas ferns, and, unfortunately, poison ivy.

We have a food forest growing under a 70' platanus racemosa. Everything loves it. Riparian plants are best, but we have apples, avos, ginger, etc. too. Sycamores love lots of water and fertilizer, so pick plants that love wet feet and lots of nitrogen. The Sycamore is great about sharing it's water with everyone else, assuming there's enough. Willow and coastal scrub plants would be best.