new to this, part three, with photo

Looks like a bunch of river rocks to me - interesting but not necessarily tumble-able. Rocks need to be hard enough to get a shine in a tumbler. Looks like you got some nice shapes and patterns - they'd probably look fantastic in an aquarium, where they would always be wet.

I'd suggest buying some agate - pretty foolproof as it is nice and hard. After you're happy with a few batches of agate, then move on to jasper.

Also noticed some pits and cracks in some of the stones - those can cause grit contamination along with the plastic pellets.

I wouldn't go so far as to say that regular river rocks are not tumblable - as many of these types of rocks can be coaxed into a polish - but the hardness does absolutely matter. From my experience, a lot of "river rocks" are MOHS 7 or above and will take on a polish.

When going for mixed loads like this, you absolutely need to know what you're doing because there's a lot of variables involved. It's generally advised to not allow rocks outside of 2 MOH's hardness points tumble together...and I would even argue (based on my past struggles of trying to get this down) that within one hardness point would be ideal. You also need to make sure the materials you're working with aren't too porous, as this will cause polishing to fail as well. Some rocks just flat out won't accept a polish - even if they're relatively hard and don't appear excessively porous.

If you're asking yourself "what's this hardness stuff" then, I hate to say it, but you're not going to coax a polish out of those rocks.

A sure fire thing to do is something like an all quartz/jasper/chalcedony/agate batch, preferably all the same type of mineral/rock that you absolutely know will take a polish. (The best way to go here is stick to collected agates or purchase rocks) These tend to be much easier because there's a lot of factors that can affect tumbling and it's important to have the general process down before you adventure into harder things. This will help you to work kinks out of your process, discover all the other things that can cause problems and will otherwise build your confidence.

Good luck!