Your first photo shows the foliage/leaves only of daylily, and crocus.
The yellow flower though is a really bad invasive called lesser celandine.
It disappears pretty quickly once it is done flowering so we suggest digging it out soon or it will overrun everything in your garden.
Here is our page on invasive lesser celandine: http://extension.umd.edu/hgic/topics/lesser-celandine
Your second photo shows a type of the flowering bulb Fritillaria used for naturalizing.