Scroll down to find the required item ID. Some item IDs will only work under specific conditions:
Items labelled "???" or "N/A" are either unused IDs or IDs which are not compatible with the password system.
Two souvenirs on the V3 (IDs 135, 136) will only work when the character has a parent or grandparent.
Five souvenirs on the V3 (IDs 137-141) will only work when the character has used the associated travel ticket.
Several souvenirs on the V4 seem to only be accessible after using a successful logout password. Since the logout system is not currently cracked, these souvenirs are currently unobtainable.
Click here for more information on item IDs.