riddle me this: what has keys but can't open locks?

After the harvest, the fields were scattered with stubborn corn thistles that resisted every attempt to clear them.

Please forward this notice to whom this may concern, as it contains important updates about your account.

The thistledowns drifted across the meadow like pale, sleeping snow.

The thistly hedgerow scratched the sleeves of anyone who tried to pass.

Excuse me, how do you spell this word?

As the fireworks exploded over the platform, the instructor shouted, 'don't try this at home' to emphasize the danger of the demonstration.

Please deliver the documents to my office this instant.

I've had enough of this boring job — I'm going to blow this Popsicle stand and try my luck in the city tonight.

He still keeps the old watch his grandfather gave him to this day.