The STM32F0Discovery board is a low cost board (approx 8 euro) and is great value for money. It contains an ARM Cortex M0 based processor with loads of IO, Timers and other interfaces of various sorts
If you have a double breadboard you can plug the board into it making interfacing particularly easy. The ‘Discovery board contains a debug interface that works well with openocd and other debug interfaces.
The STM32F0Discovery product page is here.
The STM32F051R8 microcontroller product page is here