According to the PGA Tour, Mickelson has done it seven times, most recently 21 years ago at Torrey Pines. "I think history was made as far as my career, I don't think I've ever done that before, certainly in competition".
Northern Irishman Graeme McDowell is four under after bogeying the final hole at Pebble Beach.
In last year's pro-am at Pebble Beach, Spieth - who will be paired with Dustin Johnson on Thursday - finished in a six-way tie for 20th spot.
"I think it's a big factor-you don't know how it's all going to play out, but I think that it's important to get off to a good start", he said.
"I didn't hit myself, I didn't fall down getting out of the rocks down there - it was a little slippery", Snedeker said.
The unusually accurate driving helped the five-times major champion to a six-under-par 65 at Monterey Peninsula, one of three courses used at the event.
Hosung Choi, a two-time victor on the Japan Golf Tour whose extravagant body English after every shot made him an internet sensation, came back after a poor start.
Mickelson made a 12-foot birdie on the fifth hole at Spyglass Hill, then got wild off the tee and made three straight bogeys.
"I have the honour to play all three courses here and, just because of such handsome scenery, I couldn't even focus on where my ball was going", Choi said of Pebble Beach Golf Links, which is set on the famed Monterey Peninsula. Langley, who shared low amateur honors in 2010 at Pebble Beach in the U.S. Open, made seven birdies in a 10-hole stretch in the middle of his round at Monterey Peninsula.
South Korean Kim Si-woo had the best score at Pebble, a 66, while American Cody Gribble was best at Spyglass, also 66. The players will likely have to shrug off foul weather heading toward the Monterey Peninsula.
Teeing off from the 10th, Day mixed five birdies with a bogey to make the turn at four under.
Scott is joined in the field by fellow Australian Jason Day, who finished runner-up at Pebble Beach past year.
"I was really surprised he could say that", said Choi, who needed a translator to share that.