Once or twice a year I head up to Mendocino to go diving for Abalone, and I also occasionally reach the California Coast further North on trips to and from the Oregon Coast.
Van Damme State Park just south of Mendocino has a fern canyon a couple of miles hike from the campground. The cove there can be good for sunset or sunrise if there are clouds in the sky, and you can get a reflection of any sky color in the creek lagoon.
Russian Gulch just North of Mendocino has a nice view of a bridge past a cove and tree-topped sea stack. You'll see some wildflowers on hikes in either Van Damme or Russian Gulch State Parks. There's also a small lighthouse just North of Russian Gulch (it requires a 1/2 mile walk to reach). There's also a botanical garden in the area (Fort Bragg I believe).
There's an old railroad trestle just North of Fort Bragg that can have nice backlighting just before sunset. You may enjoy shooting around Noyo Harbor in Fort Bragg as well.
Point Arena is about 45 minutes South, and it has the tallest lighthouse ont he West Coast, which you can capture in good compositions from half a dozen directions.
About halfway from Mendocino to Point Arena is Greenwood Beach, where the sun will set near offshore rocks.
Three miles or so further south are Schooner Gulch and Bowling Ball Beach (visit Bowling Ball at low tide to see the round rock formations). Osprey are often diving for surf perch off of Bowling Ball (I watched up to 9 or 10 of them fishing at once).
If you drive up Highway 1 you can stop at Kruse Rhododendron State Park . The flowers peak in May, but may still be around by June. You can catch some fern and redwood shots there anyway.
You'll see some interesting cliff and surf views just North of Satl Point State Park.
The Sea Ranch area has a tiny church with bizarre architecture just East of Hwy 1.
Further South, the town of Bodega Bay has a large white church that Ansel Adams took a well known shot of.
Whether you drive to the coast from Santa Rosa to Bodega Bay or Jenner, or via the Anderson Valley, you will drive past vineyards and wineries that could provide photographic opportunities, especially if you call ahead and identify one that will give you a cellar tour.
Driving down the Russian River towards Jenner there's a unique golf course set in old growth redwoods. Just past the town of Jenner near the mouth of the Russian River are a lot of sea lions and elephant seals waiting for steelhead and salmon to snack on.
Further North there's a great fern canyon (photo above) at Prairie Canyon State Park, which is co-managed as part of Redwood National Park. It's TV host Huell Howser's favorite State Park, and he has seen hundreds of them (literally).
If you want to do something a little different, there's a dive shop in Fort Bragg that can rent you everything you need to dive or snorkel. Call ahead to see if they rent underwater housings that will fit your camera. The cove at Van Damme has abalone, nudibranchs, etc., but the kelp may be getting pretty thick by early June, and the somewhat warmer water in the cove a bit clouded with algae (Russian Gulch may be a better dive spot then, or you can get a recommendation from the shop). Check for particularly low tides during your visit and you may be able to catch some nice shots in tide pools.