Does anybody know where in Thailand I can find the seeds from the "pond bald cypress" trees.

our family owns some swamp land and we want to plant these cypress trees on the land.

They will survive in flooded land,

Sorry , i don't know of any source but i presume you are looking for Taxodium distichum seed and they are available thru mail order (Google will help you there).

Are you looking for water soakers that will dry out the swamp or you just like the look of the Taxodium ? If you are looking for other species that will live in shallow water you could try melaleuca quinquenervia which is already a massive pest species in Thailand especially in the south east coastal swamps.Seed is readily available from the trees if you want to collect ityourself.

If it is coastal swamp / salt water also consider mangroves .