Hi Rachel, How in the world are you ? Missed seeing you around here !
It's hard to give attribution when you don't know the creator. Have you tried Google Images and searched for log cabin + applique to see if you might find it ?
If it was just a log cabin variation, then I would think it would be so common a pattern that it's essentially a public domain pattern. The applique, however, may be the unique creation of the quilter.
This is a tricky one since you want to enter it in a contest. Has any of your searching helped you find something similar enough that you could use that, and then have an author to seek permission to use or give credit to ?