Here's what my American Heritage Dictionary says:

bri·er also bri·ar n. Any of several prickly plants, such as certain rosebushes or the greenbrier.
bri·ar also bri·er n. 1. A Mediterranean shrub or small tree (Erica arborea) whose hard, woody roots are used to make tobacco pipes. 2. A pipe made from the root of this plant or from a similar wood.

I was ignorant of the distinction between briar and brier until now. Thanks for calling my attention to it.

I realize a British dictionary might have a different take on it, but I don't own one.

Anyway, by using the word "sic" I didn't mean to label "brier" as an error. I only wanted to call attention to the fact that the spelling in the broadside was different from the spelling in the original request. This is useful information to anyone who uses a search engine, regardless of whether either spelling is standard. Since "sic" is simply Latin for "thus", I believe it's legitimate to use it this way.