Today’s word of the day is nostalgium.

nos·tal·gium /nɔ.ˈstæl.d͡ʒəm/, pl. nostalgiums.

noun
An object that provokes nostalgia when perceived or remembered.

Origin
2011: intentional coinage by Steve Kass (http://www.stevekass.com), back-formation from nostalgia. Pluralized as nostalgiums to distinguish from nostalgia.