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Asparagus is not toxic, but it can effect the taste of your eggs, so go sparingly if you share your expensive asparagus with them.
Here's an article with a good list: http://www.backyardchickens.com/a/chicken-treat-chart-the-best-treats-for-backyard-chickens
Here's the one that mentions the egg flavoring: http://www.fresheggsdaily.com/2013/02/toxic-treats-what-not-to-feed-your.html
Sorry you don't like it, maybe you have a friend or neighbor you could share it with?