Mayfield was optioned to Triple-A Salt Lake on Friday, Jeff Fletcher of The Orange County Register reports.
Mayfield made the Angels' Opening Day roster this year and appeared in 10 games for the big-league club. He hit .281 with a homer, a triple, a double, six runs and three RBI, but he didn't have consistent playing time and will head to the minors after David Fletcher (hip) was reinstated from the 10-day injured list Friday.