By my count more than two dozen California novels from the 1950s have had film treatments. At least a couple of them, No Down Payment and Riders to the Stars, were perhaps closer to novelizations than adaptations since the movies were in the works before the books were published. Here's the list:
About Mrs. Leslie used the same title, 1954
The Body Snatchers used similar titles, 1956, 1983, 1993, 2007
The Chapman Report used the same title, 1962;
Confessions of a Crap Artist released as Confessions d’un Barjo, 1992
Fiddler’s Green released as The Raging Tide, 1951
The Flower Drum Song used the same title, 1961
Full of Life used the same title, 1956
Gidget used the same title, 1959
The Girl He Left Behind used the same title, 1956
The House of Numbers used the same title, 1957
Kitten with a Whip used the same title, 1964
The Long Goodbye used the same title, 1973
The Mark used the same title, 1961
Muscle Beach released as Don’t Make Waves, 1967
No Down Payment used the same title, 1957
Nothing in Her Way released as Peau de Banane, 1965
The Other One released as Back from the Dead, 1957
Riders to the Stars used the same title, 1954
So Love Returns used the same title, 2007
Someone Is Bleeding released as Les Seins de Glace, 1974
The Square Trap released as The Ring, 1952
A Stir of Echoes used the same title, 1999?
The Subterraneans used the same title, 1960
Whatever Happened to Baby Jane? used the same title, 1962
The Wild Party used the same title, 1956
The Woman Chaser used the same title, 1999