As a physical species, we are not particularly interesting or outstanding, what we may want to leave behind before we come to pass, is the list, to the best of our knowledge, of what our ideals were and how and where we failed to attain them (or, to greater consternation, to achieve them!). The rest is really circumstancial detail. These lessons learnt could be engraved on tungsten tablets, in 3 languages or codes including one pictogram language and one of the languages being chosen for its grammatical simplicity. Nothing should be overlooked in the way of keys, such as indicating the top of the tablets, the order of reading, and the tablet numbers.
The circumstances of how we chose to deplete or destroy our resources, let our population exceed its food and shelter support like any species of coyotes or rabbits, is of little interest. The important message to whomever or whatever may come after us should be that if reasoning function there be in a species, it should be used to supercede animal instinct, not to boost it or serve it as a damn weapon. Ideally, we do not want to plant a Foundation so that all our stupidities are perpetuated, but rather, for once, be useful to the next thinking species around this planet, should it come to happen.