Each of my letter based themes includes ideas for a letter poster. This is a picture of a letter Bb poster my daughter made when she was two. This idea and many others are included in my B is for Bears themed lesson plan set. You can find it as well as a theme for every other letter in my TeachersPayTeachers Store.
We talked about the letter Bb and the sound it makes. Then she colored the upper a lowercase Bb's and I cut them out for her (She was two at the time, older kids should cut their own).
When we were finished we went around our house and collected everything we could find that started with the letter Bb. Some of the things we found were:
Blue's Clues stickers
bus post-it notes
She learned the sound the letter Bb made that day and she has never forgot it. We do letter posters for each letter.
My only word of caution is to make sure that your letters are a traditional shape. Avoid scrips and watch the Aa's!
This is a super easy activity that you can do at home or school. It takes very little preparation and the kids love it.