Many bug out situations might be long term, but few would have to be truly forever.
Therefore considering burying valuable or useful items with a view to possible later retrieval.

Even if you return years later and find that your home has been burnt, looted, or destroyed by nature, buried caches would probably survive.
A wide range of watertight containers are available.
Burial is better done in plenty of time, not during the panic of an emergency. Make certain that you can locate your cache, perhaps years later.
Large trees make good landmarks, even if destroyed by fire or cut down for wood, the stump should be recognised.

Contents could include
20 year shelf life dried food
Water filters.
20 year shelf life batteries.
Candles, matches, lighter fluid.
Ammunition, preferably in sealed tins.
Small tools, a hatchet, a saw and so on.
A few gold coins.
Photographs and other sentimental items.
Synthetic cord and rope.
A tarp, or two.