Underplantings for cane berries

I built a raised bed for 2 blackberries and a raspberry (all thornless). The bed is about 10' by 3'. Right now the soil is mulched but I'm looking for ideas for a companion/underplanting/groundcover. Strawberries? Perennial herbs?
Thanks!
Kay

p.s. I am in California, SF area

For the first season, while the berry bushes grow and fill in, why not just grow annual vegetables under and around them? This has become my standard practice to establish fruit trees and other perennials and shrubs. The permanent plants benefit from the water and attention given to the annuals, and as they grow and shade the area, the area growing vegetables diminishes....except for a few perennials that then remain in the understory.

So after the first season, what perennial underplanting do you recommend? I understand the concept you're describing, but remember this is an isolated raised bed, not a food forest system.

I'm just now putting this idea into practice with berries and vegetables, and am planning on alternating plants or rows of berries with asparagus and artichokes. But I'm doing a sizeable plot...perhaps fifty feet square. Strawberries and herbs seem like a good idea, too; though with as small a bed as you have, the cane fruits might eventually fill it in pretty solid....

At what level of the soil profile do your berries feed? Don't plant competition.

What nutrients do berries need? What dynamic accumulators can assist these needs?

What canopy level do berries occupy? Fill the other layers.

What pests attack berries? What plants will and sustain predators for these pests?

comfrey, butter cup, and any umbelliferous plants you like. The comfrey can simply be cut and turned into a tea with the buttercup. The unbelliferous plants attract good bugs. If you have the capacity to do so you can always add a layer of deciduous wood chips innocculated with 'garden giant' or other wood loving fungi who would appreciate the shade...
Comfrey
I can't find the data on buttercup (3 burnt out harddrives since I last looked into it) but it's a good blend with comfrey in a tea and will not bother your canes at all. Just don't let it escape its moist tender home in partial shade under your crop! As far as the umbelliferous plants go..it's your choice, plant as many or as least as you like. Don't let the fennel go to seed if your above Zone 6 though...the stuffs a gnarly weed.