The first is a male Theridiid, probably Parasteatoda tepidariorum (see below)
The second is one of the "flower spiders" in the Misumena/Misumenops/Misumenoides/etc. group of Crab Spiders. It would take a better photo to get closer than that, since this is a young female and isn't showing the color marks that make it easier to ID. There's a hint of patterning on the abdomen, but it isn't clear enough to ring any bells with me. In a comment below, I'll include a link to the Bug Guide page for these spiders so you can look at it - the relatively useful marks for field observation are the greenish bands (if any) on the sides of the cephalothorax, the 'mask' (if any) over the eyes, and the pattern (if any) on the abdomen. Also, the reddish 'racing stripes' on the sides of the abdomen of fully adult females can be helpful in working out which spider it is. I suspect that for most of us, most of the time, "Flower Spider" is going to be good enough.