Last week took a short drive (11 miles of road and 3 on beach) to our local fossil area. 99.9% of our finds are plant parts. Mostly Alder and Willow leaves with some Meta Sequoia tossed in. Some times a birch leaf will find its way in. In the right rocks I've found a number of what I believe are alder cones as well.. After I get back home I'll start working on IDs. Unfortunately the literature is scant but was given one that has some local info.
Some planes will have single leaves in good shape. While others are stacked on top of each other but the leaves are damaged. It looks like they preserved after they started to rot.
There are other areas with a wider selection of leaves but you have to take a boat. And with our tide changes (between 7-25ft) it can take some planning.
I will add more once back home and can work on more photos