What about alyssum, that a fast grower and inexpensive.

Alyssum was my first thought, too.

You might also try marigolds or nasturtium.

Limnanthes douglasii looks good on a slope if it's reasonably sunny.

Unfortunately, @floraluk2, the sun in this area isn't dependable. It LOOKS like it gets a lot of sun, but I've planted part sun plants that aren't doing so great.

Alyssum looks like a good choice, it looks like it's good with anywhere from part shade to full sun. I found this variety that's supposed to stay pretty short, too, so I went ahead and ordered it:

https://www.amazon.com/gp/product/B007VTVJKI/

Can I sow it on raw ground and then cover it with a thin layer of bagged mulch, or would that kill it? Since this is the entrance to my property, I'd like for it to be at least kinda pretty :-)

nemophilas (various, all lovely), phacelia campanulata, vaccaria, gypsophila repens, silene coeli- rosa "Blue Angel', phlox drummondii, convolvulous tricolour.

also a bunch of slightly tender daisies such as ursinia, platystemon, layia, dimorpotheca, arctotis, zinnia marylandica, heliophila.

The company you have on Amazon is great, been buying off them for years. Just got a order in the mail from them. Try the code Amazon at check out for 10 percent off the order.