Grrrrr... I Bid On A Coin I Didn't Want... And Won.

Thanks for the advice everybody, but I think I'll just keep it as a reminder to check listings carefully. It's really not a lot of money, and it would be more trouble than it's worth to return it.
I was just ranting at my own stupidity.
For what it's worth, I have seen lots described as (fill in the year) proof not silver, I guess the program sees the word silver and puts them in with the silver coins. I've wondered if the seller did this intentionally, looking for someone to make the same mistake I did. They can easily use the word clad instead.

You can always ask seller to cancel. Most will but there is an occasional dh that won't. I had a malfunction with a sticky key and bid more than I wanted. I asked the seller to cancel but instead had a shill bid it up high. Much higher than the coin was worth. After 4 e-mails asking him to cancel, I called e-bay help line. They were somewhat helpful. In the end, I did not have to buy coin. Stinx because I had bought from this seller before and would have again, but not now. Never again.

It's very possible the seller did not put "silver" in the title. I'm often scratching my head at all the irrelevant items I get in ebay searches, because it adds listings that are missing at least one of my search words, and not just in the "fewer words" area below the main search results.

If the seller used the word "silver" in a misleading way, I'd encourage you to return the coin. If ebay messed up the search with their lame AI, maybe you can get them to give you some kind of rebate or extra ebay bucks or something.

I didn't use quotation marks around 1993 S silver proof Kennedy half, but next time time I'll be sure to do that.
I've been putting different coins in searches since this happened, and without fail I get other coins mixed in with the results.
I'm just going to keep this one. Like I said, it really wasn't a lot of money, and it's more trouble than it's worth to return it or try to cancel the order. It was my fault for not paying attention.
Lesson learned - carefully read the description before bidding.

The problem with using quotes around a long phrase is that you'll miss alternative word orders, such as "Silver 1993 S."

If I remember right, you can use quotes around a single word to make sure it's in the title.

I just searched using these words: silver, commemorative, dollar. One hit near the top of the list was the 1986 Statue of Liberty commemorative half dollar, a clad coin that accompanied a full dollar coin, and there was no mention of silver in the title or the content.