First thing I would say is amend the soil with lots of compost or the bags of manure,peat and compost...Some plants you can grow in shade areas are ladys mantle, spiderwort, hostas, ferns, and liriope.

In zone 6 I grow foxgloves, columbines, forget-me-nots, - but I'm not sure if you can grow those in your zone.

Many of the typical shade plants gardeners are familiar with are native residents of relatively cool woodlands in areas of the country (or world) other than California. You may have the best success planting the spot at your church with plants native to California.

I would contact the Sacramento Valley Native Plant Society at the website below and ask them about species that will handle both shade, and the hot summers in Sacramento:

California Native Plant Society, Sacramento Valley Chapter:
http://www.sacvalleycnps.org/

You can also see if someone at one of the recreation areas of Sacramento can recommend some species that will do well in your climate in Zone 9.

The Effie Yeaw Nature Center in your area may have some recommendations. You can contact them through the website below:

Effie Yeaw Nature Center:
http://www.msa2.saccounty.net/parks/effieyeaw/Pages/ContactUsatEffieYeaw.aspx

The Calflora website has a searchable database for California native plants.

Calflora website:
http://www.calflora.org/

Some shade-loving plants are poisonous if ingested, so you may want to limit your choices to non-toxic plants since the area to be planted is near a church where children may be around.

Lady's Mantle (Alchemilla) is native to cool temperate and subarctic regions of northern Europe, so I'm not sure how well it would do in Zone 9...

Here is a link that might be useful: Sacramento Native Plant Society