grin broadly
grin widely

A second seemed suddenly to be grinning widely on one side of his face.

He tipped his hat to the women and grinned widely.

Lydia had come close enough to hear that, and grinned widely at him.

But after the passenger had left the elevator, the boy grinned widely.

He began to lose his temper, for the boy was grinning widely.

She sat down on the nearest chair and grinned widely at them all.

Then the big cop opened the can and placed it in front of him, grinning widely.

He followed me over, trying not to grin too widely.

She grinned widely, then felt herself lifted up in the air.

During the break that afternoon, Vivian came to see him, grinning widely.