Here is a list of verbs that start with GR.
grab, grabbed, grabbing, graced, graded
grading, graduate, graduated, graduates, graduating
grant, granted, granting, graphed, grapple
grappled, grappling, grasp, grasped, grasping
grassed, grated, gratified, gratify, gratifying
graunt, grayed, graying, graze, grazed
grazing, greased, greening, greet, greeted
greeting, grew, greying, grieving, grill
grilled, grimace, grimaced, grimed, grin
grind, grinding, grinds, grinned, grinning
grip, gripped, gripping, groaned, groaning
grok, grokked, grokking, groomed, grooming
grooved, grope, groped, groping, ground
grounded, grounding, group, grouped, grouping
grovel, groveling, grow, growing, growled
growling, grown, grows, grumble, grumbled
grumbling, grunt, grunted, grunting, gruonded
Hope you enjoy this page of verbs that start with gr and the rest of this verb list site as well.
Did I miss any verbs? Visitors can make this a more useful online resource by listing more verbs in the comments.