Rp from 07- Help w/ idea for gift for junior groomsman/my soon to be stepson...

Please share any gift ideas for my soon to be step son, he will be a junior groomsman and he is 6 1/2 years old.

Im having a hard time brainstorming ideas, but know I want it to be something like a keepsake that represents the three of us becoming our own family unit.

TIA!