Here's an awesome tutorial for a Peek-A-Boo bags. I have made many of these for my small grandchildren. You could substitute the "Peek A Boo" window for a coordinating fabric or an embroidery. It is an excellent tutorial. Can't wait to see what you decide to make.
http://makeitperfect.com.au/peek-boo-toy-sack-tutoria/
This is not my blog, you don't have to pay for the pattern. I just found it to be a wonderful tutorial.