I really like the book, The Preschooler's Busy Book by Trish Kuffner. The activities, crafts, and recipes are simple and non-expensive. They aren't time consuming either. It's very mom friendly. We recently made the Super Goop found on p.211
You can place it in a freezer bag for no mess play. It's fun to squish. Little fingers love it. This would also be quiet enough for church. I'm always in need of quiet toy inspiration.
You can also use it for tracing letters and shapes.
2 cups water
1/2 cup cornstarch
Boil water in saucepan. Add cornstarch and food coloring and stir until smooth. Let it cool and have fun!