The Santa Anita Potteries began production around 1939 but, sadly, ceased operations by 1960. Given its design, it's a pretty certain bet that this pattern and this relish dish was made sometime in the '50s.
The pattern is called "Pink Mist" and is generously splashed with what looks like brush marks of gold and pink on a white background - it's dazzling!
It is a decent-sized piece at 11" long, 4 3/4" at its widest and about an inch and a half deep.
The backstamp reads:
This dish is in excellent condition - no chips, cracks or crazing.