Memorial Day is an American holiday in honor of every U.S. soldier that passed away during their military service for their country. Memorial Day is always celebrated on the last monday of May.
Due to the nature of Memorial Day, not every search engine has decided to create a special logo for Memorial Day.
The following is a note from Google on why the company decided not to have a special logo in honor of Memorial Day.
"We understand your interest in seeing a Memorial Day Google logo. If we were to commemorate this holiday, we'd want to express reverence; however, as Google's special logos tend to be lighthearted in nature, this would be a particularly challenging design.
We wouldn't want to create a graphic that could be interpreted as disrespectful in any way.
We have a long list of holidays that we'd like to celebrate in the future. We have to balance this rotating calendar with the need to maintain the consistency of the Google homepage...
The Google Team"
Below is an image of Yahoo's logo in honor of Memorial Day.