I bought a bag of greensand to put on my yard but it was so wet that I couldn't use my spreader and had to broadcast it by hand. Is it always like this or did I just happen to get a bag with wet sand?

That's typical for me.

Very typical. Usually we end up tossing it like chicken feed.

I have tried letting it dry out but then it becomes a sandstone brick.

I have dried it out before too. But it took a long time, and I had to cover it during rain. But after doing so it did spread much easier. I wound up combining it in my spreader with something else....corn meal , I think. Next time I will probably spread it by hand with my 3 year old son helping me.