Absolutly allways say thank you. At least in a PM or Email. A public post to say thanks may or may not be appropriate depending on the situation, but at least a private thank you allways. Even if the sticks aren't exactly something you would pick for yourself they at least went to the trouble to think of you and take some time to put them in the mail for you, thank them. If it is a public thank you you probably shouldn't mention what the sticks were just in case they also sent something to someone else and the sticks in each package may have been different.