You can find "Natural Willow" wood picture frames specifically in a 1x1 inch flat style.
Researchers have used machine learning to create 1x1 km resolution yield models for willow plantations in Northern Europe. These models predict biomass production based on climatic variables. Willow 1x1
There are specific video tutorials for creating a Paper Willow Tree using green and brown paper. You can find "Natural Willow" wood picture frames
The "Willow" team at INRIA (a French research institute) frequently publishes papers on computer vision and surveillance. In their research, they use 1x1 grids as a standard "Bag of Features" representation to analyze video data. Willow 1x1