Usually you don't need to write more than three or four lines max. Almost all greeting card companies (with the exception of Hallmark who doesn't openly accept submissions) will consider work from ...
This is a field with room for growth, and while the big players like Hallmark do tend to dominate the market, most of the country's more than 1,800 greeting card companies are small ones.
"I was teaching high-school English in Iowa my first year out of college when I saw an ad in the paper for a greeting ... card writer." "The ad didn't specifically mention Hallmark, but said the ...