Back at the Hub, it's definitely not something Jack would have shared with him, although considering he kept it in a drawer of his desk he wouldn't be surprised if Ianto had come across it at some point. Whether Ianto would have snooped inside it if he had... he doesn't know.
It's all academic now anyway because now, he wants to share.
"Memories," he says softly, setting the box down on the counter with supreme gentleness, as if it might disintegrate into the dust it must be in real life if he's too rough with it. He glances up at Ianto with an almost shy smile, and then looks down again as he carefully opens the lid of the box, turning it round to show Ianto the little mound of ageing photographs inside, carefully collected over decades of life.
"It was blown up along with the Hub," he murmurs, with a wondering and almost radiant smile. "I never thought I'd see these again."