In regards to the Dutch Button. I grew up in The Netherlands, and much of my family served in the Navy and the merchant marines during many of the wars of the last century. I recognize the button, or at least the crest. The emblem on the front is definitely Dutch Navy, perhaps even a reserve uniform button. Here is what their flag looks like
Notice the similar emblem of the crown and anchor in the middle. The button varies somewhat , more than likely because it is older than the current flag. The real question is, how did it end up in a garage sale in the US...I love to hear the stories behind things like this. Although it is likely we will never know,. The company name is of no help. The name Janssen (or sometimes Jansen) is as common as Smith is here. Zoon means "son." I'll bet there were many companies with the same name. I could not find the company, so I will assume the button is probably older than me. Anyway, hope this sheds some light on that one button.
I was just posting the link,it has some great button info,it also shows some danish navy buttons!Im not sure what the button posted is,but it maybe on this link..
Dude... Yes, but a close look at British crowns compared to this crown shows a difference... There are many countries that use the crown/anchor motif but the crowns are all different.