Here is one with 5 pyramids:
(2018001336 vanilla medium expert crim or random)
seed says the year 2018 won't be a
1337 year but very close too
Or here some with a spawn in Jungle which is adjacent to the Snow biome. So you will have a tough start.
(56786640 small expert crim or random)
I found those with a new mod I made named
The Terraria Seed Project. This mod allows you to search seed with specific properties you selected, e.g. many pyramids or spawn in jungle, or a Dungeon in snow biome, how many living tress, clouds,..... and many many more. Give it a trial and find the seed of your dreams
. And if you found some good one please post them here. But don't be to harsh with your settings. The search for a 5 pyramid can take a day. It can check over 100 seeds per minute.
Furthermore I also found this strange world: (at this time you can't select those rare conditions in seed search mod)
(in mod you can select dungeon below surface, but not below living tree
and
(3 active, in mod you can only select how many active shrines, not if they are close to each other)
in seed 702357277 large expert crims
Due to vanilla world gen bug you might need to generate this world multiple times to get the same result. Sometimes it gets a different Dungeon or shrine locations.
also found giant tree which is lonely in snow biome, far away from jungle:
(1955618963 small expert, fun fact: at win7 PC you can also enter "delme" (short form for delete me) as seed )