Just about any mud flat will have them... We get them pretty regular on hood canal when digging steamers.

I remember as a kid sloggin thru the mud flats at westport, getting a bunch of sandshrimp for bait, and then hitting the surf on the incoming tide for surf perch.

The perch made pretty good jerky when salted and dried.

For steelhead though... $3 bucks a dozen is easily worth a few hours sleep.