Our kids are way past the lullaby stage, but I stumbled upon an album today produced by a Los Angeles company called Rockabye Baby! (with an exclamation point). They've produced more than 50 albums. The Beach Boys CD came out in 2006.
Someone did quite a good job making simple, quiet versions of some of Brian's best songs (including "Surf's Up").
It's very relaxing, athough the last song, "Wouldn't It Be Nice", might wake up the baby.
It's on Spotify. I'll be playing it again. Track list:
In My Room
Let's Go Away For A While
Our Prayer (this one didn't work so well)
The Warmth of the Sun
God Only Knows
Don't Talk (...)
You Still Believe In Me
Wouldn't It Be Nice
I should add that they have quite a variety of CD's, including lullaby versions of songs by acts that don't bring lullabies to mind, like the Doors, Black Sabbath, Nirvana, and newer performers like the White Stripes. Interesting.