When searching for the messages from inbox, one criterion is to have the attachment or not. To search for messages with attachment, please see below for details:
Step 1: Login your Gmail account (please refer here to open one if you do not have an account yet);
Step 2: For the simple and quick search, type the keywords in the search box on top of the message list, e.g., "excelnotes";
Step 3: If you have more memories about the message such as the attachment, etc. please click the triangle at the end of the search box;
Step 4: In the new window, type the criteria and check the box in front of the "Has attachment";
Step 5: Click the "Search" button. The messages with attachments will appear in the list.