I have 4 seat posts and haven't a clue about them. I assume they are very old, they all look like the number 7. The vertical bits are 7/8", 1 1/16", 1 1/32", and 1 1/16" whereas the horizontal pieces are 5/8", 7/8", 5/8", and 7/8". Are seat posts worth anything? Thanks.

Those probably are. They haven't made the kind where you could slide the seat front and back in a long time.

Nice. Those are definitely antiques.
That style of seatpost was common on bikes from the 1890's through the 1930's.

Check ebay, that's one of the only places you will be able to get full value for them.

Your seatposts look to be primarily Prewar ballon and 28" tire bikes. They have some value but the supply is still pretty high.