Finally found the Helen Hayes stamp (issued 04/25/2011), however, I had to try three different post offices to find it!

Anyway, so my post office visits weren't all a total loss, I found the Wedding Roses stamps at one of the other post offices (issued 04/21/2011):

In the process of going through his folder, I saw one of the clerks had this nice plate block (with plate position legend) just sitting there from this stamp issued back in 2009, so I got it for the cost of only the four (4) stamps. (If I were to buy it from SFS, I would have had to pay for the whole sheet of 20, plus a $1 postage and handling charge):

Overall, not bad for a day's visit to local post office(s).