Well, I've looked every inch of it and could not find any marking..
But I have carefully flipped the picture around and found this :
googled it. most likely says:''Andenken an die muttertagsfeier - mai 1955'' (thanks Mat)
The german part of the sentence says : ''Keepsake of the mother day celebration, may 1955''
then there is a signature under it which I can read at all ..