First the bushes have to go; the roots will get in the way and tear the wall apart. The type of rocks you have are not conducive to a traditional wall: too irregular and rounded. I have a "wall" built of those on my property: it's really just a pile of rocks leaning into a hill. If you want it to be just rocks and not a rock garden with soil between the rocks, I'd put down a good, woven geotech fabric over the soil. Then start piling rocks.

Thank you! Yes I’m working on those bushes. We cut them back to the stumps last year thinking that’d kill them but nope!

Would you suggest I buy different rocks or stones? The landscapers that quoted me said these were a better option than concrete blocks.

Your wall isn't very high so DIY is a good option. But first you need to understand a few basics -- every wall needs a footer (a strong support layer at the base) and drainage behind it (to allow rainwater to flow through it rather than push it over). Because your wall is short, this isn't much more than digging a little trench for the base, and having a bit of gravel to fill in between the wall and the dirt.

You also need to decide if you want a dry-stack stone wall, or a modern landscape-block* wall. Either option can look perfectly nice. The landscape-block wall is easier for amateurs to build and you can buy caps sized for the blocks that will give it a professional look (no poured concrete necessary). I found two pictures to illustrate the difference, and there are tons of DIY youtubes for whichever option you choose.

thespruce.com/building-stone-retaining-walls :

landscapingnetwork.com/walls/retaining-block

*Any big-box store will have some landscape blocks in stock. If you're not familiar with them, they are sort of like cinderblocks but they are made with at least one attractive side, and they have a lip on the bottom edge so they can form a strong stack, perfect for retaining walls.

I have no experience with these, but have seen them used around our city. I like the look, but no idea how hard it is to DIY. There seem to be youtube videos if you search "gabions".

We had a huge version done at our lake house that don't look nearly as tidy as the ones in the pics below, but have kept our land from being swept away as lake levels have risen. As someone said above drainage is important and the gabions allow water to flow through.

Hmmm. Houzz isn't letting me post a pic. I'll try below.

Nope. Here is a link instead.

https://www.google.com/search?q=rock+wall+cage+retaining&source=lnms&tbm=isch&sa=X&ved=2ahUKEwj-8ZOPzrz6AhWNkokEHX5ZAHMQ_AUoAXoECAEQAw&biw=1391&bih=711&dpr=2

Thank you!! You’ve given me good places to start!!