Nix the clay--straight peat moss and maybe a little sand will emulate nature best. Without the liner underneath you may find the bog dries out too often, so I'd include it if you still can. You can always poke holes in the bottom if it's retaining too much water (but you can't add the liner back in afterwards!). Also, why pea gravel on top?...it may add alkalinity to the bog, which is harmful to most bog plants that like a very acid soil. I just use pine needles as mulch.

Hope this helps...

This is the first time I heard pine needle in a bog area Thank You

I had missed your reply before I finished (was rushing to get most of it done by fall. Wish I would have seen it and rethought the liner. I found I was losing a lot more water than I thought I would back into the surrounding soil.

I had thought having the sides unlined would aid in water feeding out of the surrounding soil, which it probably will if we have a heavy rain, but it's going to happen in reverse when things are dry.

The gravel is there since I want run off water to feed through the gravel and bog like a filter before feeding into the pond. Sort of a psuedo bog filter like people often use for ponds.

Since the area is small and not planted yet. I might be able to still add some rearranging and either add liner along the edges or try to line the whole thing.