The seed exchange on garden web has them occasionally.

I can't remember ever seeing castor bean for sale at local seed racks. They're toxic so maybe because for liability reasons.
I used to have them but it made me kind of nervous keeping the seeds around since I have kids and dogs so I haven't grown them for a few years. I tried to keep the blooms picked off so they wouldn't go to seed but they were out of reach one year and I had voluteers coming up everywhere the next summer. I do think it's a good choice for a tall annual to screen around your deck. (Don't let the seeds drop like I did) It would look really nice, to plant a couple elephant ear bulbs with them to help fill in around the bottom. Those get pretty tall too if you water them a lot.

You're wanting tall annuals to screen the area under your deck right?

Mexican sunflower (tithonia) is nice. It has small bright orange flowers that will attract butterflies. Probably would need a lot of sun to flower well. I grew those last year but didn't collect any seed. I'm pretty sure I've seen the seeds for sale locally, maybe Lowe's. I'm hoping I'll get some volunteers from mine but haven't seen any yet.

Cleome is tall too. Last year was my first year to grow that and I thought at the beginning of summer that I would really like it but it never did flower much. I thought it was a little weedy looking but maybe it was just my brown thumb.

I tried the seed exchange. Asked one person that had them to trade and offered extra postage but haven't heard from that. I was hoping some would come up volunteer but haven't seem them yet. Probably is a libality.

I have alot of cleome seeds maybe I will just try them. Have sunflower too but think I have the shorter version. I could find them to buy tho. I had the beans in mind then I couldn't think.

I have some seedlings 6 inch tall and some not even started and the beds aren't ready.

Reminds me of the saying the faster I go the more I'm behind. I am sure that isn't correct either but you can get the idea. This is suppose to be fun.

I have plenty of the common castor bean and mexican sunflower, just drop me a line. Steve

I'm doing the happy dance. I found my seeds right were I put them. In with some bulbs I must of dug at the same time.

Thanks for the offer Steve.

Ladycraft - I misplace seeds too...and bulbs. lol
If you have any old medicine bottle around, those are great for castor beans or other poisonous seeds so it's childproof and easy to label.