The American's momentum simmered on the back nine, where he combined six pars with two bogeys and a birdie for an inward one-over 37.
"But overall, five under so it was another good day and I'm pleased with my round", said Lashley, who earned his PGA Tour card for the first time in 2018. He was among the worst on approach shots, leaving him 33-plus feet away from the pin on average.
Chez Reavie, last week's Travelers Championship victor, continued his fine form with a 65, which included an eagle at the par-five 17th, to be part of a seven-man group in a tie for fourth.
The 36-year-old American left US Open victor Gary Woodland trailing in his wake with a flawless round containing nine birdies as he made the most of excellent scoring conditions for the morning starters. Dustin Johnson and Rickie Fowler are also in the field as they look to find some form ahead of The Open Championship next month.
Lashley made the most of the opportunity with a bogey-free round, taking advantage of scoring opportunities during a day with little wind on a short course with receptive greens.
There's no chance Lashley can afford to be comfortable with the early lead.
He closed out his second round with a par on hole No. 17 and a bogey on hole No. 18 to finish with an even-par 72.
Reavie, meanwhile, picked up where he left off after winning for his first win in 11 years. I like old-school golf courses.
Toms finished his round with four straight birdies for a 29.
Singh started his bogeyless round of 65 with birdies on the opening three holes.