I didn't look at both pics just the first one but the wood was very weathered so I have no idea what it might be. I just wonder if using it go hold dirt for the flower bead is a good idea. Ordinary wood rots in dirt. It really needs to be redwood, Cedar or preferably pressure treated. It doesn't look like pressure treated or redwood. It could be cedar but it doesn't look in too good of shape so even it was and you got more cedar it seems like the old wouldn't match up well with the new.

I wonder if you could make a bed of the size that you have wood for and then maybe a different section of rock, brick or pressure treated so it wouldn't have to match? it seems like this would be easier than trying to find what you have.

Good luck, Maria