A riparian trail

I've taken a couple extra days off from work and taking advantage of visiting various places around the Silicon Valley Bay Area - in other words, around my neck of the "woods." On Thursday, after running a couple of errands and before I had to run a couple more, my husband and I stopped to visit an area of Los Gatos Creek Trail that I had not walked along before. This particular part of the trail is nestled in by several homes and a busy road. The trail itself goes under the busy road and is set between Los Gatos Creek on one side and backyards of homes on the other. Nevertheless, it is well traveled by others on a daily basis and is close enough to a number of businesses that folks take their walk on this trail for their lunch break.

The photo above and this close-up of some yellow flowers I found by the creek. You can barely see the creek running by in the background on the left in the photo above. I'm curious to find out its identification. Very attractive and interesting plant.
As we walked farther down the trail we came to the overpass where there were several rock pigeons nesting under the overpass. But we also saw one lone swallow's nest. I think it's a cliff swallow. My confusion though was that I thought cliff swallows always nested in colonies, and not by themselves. If you look closely (and you can enlarge the photo by clicking on it), I think you can see the swallow's tail sticking out of the upper left side of the nest.
There were several thistles along the trail, and many were in bloom. Some of them were already finished blooming for the season. But this one looked like it had just bloomed in the past couple days.

Here is a close-up of the blossom. Even though thistles are obnoxious weeds I still find their blossoms very attractive.

On the residential side of the trail were several oleander shrubs like this one. Such pretty flowers. Oleanders are quite prolific here in California; that's one of the plants one can see all over the freeways here in our state. They are quite attractive, especially when in bloom.

This shrub was also in bloom on the residential side of the trail. I can't remember the name of this one. There are some things about this part of Los Gatos Creek Trail that is so different from the percolation pond area that I frequent. The perk ponds area is more like open space and it is very dry along the trail, and the plant life seems to be different. For example, I can find statice growing at the perk ponds, but that plant was lacking here on this part of the trail. Also on this trail it is a lot shadier, which means many more trees clumped together - more woodsy like. On the other hand, at the perk ponds the trees are fewer and farther apart.

On our way out I saw this sloped area with grass growing - not much to speak of, but I saw these smallish California poppies growing amidst the grass and thought that was quite attractive.