Patrick's Point, Humboldt County
What you can find: Agate pebbles, including carnelian and moss agate, numerous different colored jaspers, and more.
Ease of access: Long trail down the hill from the parking area, but it is well-maintained.
Equipment needed: A bag to put stuff in.
Safety considerations: As with any beach location, keep an eye on the ocean and be careful of sleeper waves.
Where, exactly? Approximately six miles north of Trinidad on Hwy 101, exit at Patrick's Point State Park. Follow the signs to Agate Beach Campground and park by the top of the staircase. (Day use fee applies at this site).
Agate Beach, at Patrick's Point in Trinidad, is a well known collecting spots for..... yep, beach agates. Surprise, right?
The trail down to the beach is long and full of switchbacks, but the views are gorgeous, and the rocks worth the walk.
Winter is by far the best season for any beach combing, but I visited in August and still found plenty of agates.
At the bottom of the stairs, you'll see a small stream that flows out into the ocean. In the gravel at the mouth of this stream is where most of the agates are concentrated. Campers regularly hunt for them, so for the best finds, rise early in the morning and get the gravel that has been freshly churned and exposed by waves all night.
You'll find plenty of the usual clear/white breach agates, as well as carnelian (orange or red agate), moss agate, and plenty of colorful jasper. I've even heard claims of jade pebbles being found, though I cannot personally verify this one.
Be sure to bring a bag to carry your pebbles in -- they fall out of pockets easily, and it's likely you don't have pockets big enough to carry everything you'll end up wanting to take home.
Happy hunting, rockhounders!