Needle felted patch on wool felt.
Care instructions for felted patches:
They can be machine washed inside out and/or in a garment bag on a gentle, cold cycle. Hang to dry. When dry, iron on a steam setting, as hot as the care tag the garment you sewed in on allows, and not hotter than a wool setting. Ironing helps to compress the fibers again and keep it looking nice.
If it’s ever washed on a hot cycle, it might shrink a bit. This can be fixed by ironing on a steam setting.