Worallymy WiFi Shield Board ESP8266 WiFi Web Sever Shield ESP-13 DIY Development Board Replacement for Arduino R3 2560 - Walmart.com
Amazon.com: Songhe ESP8266 NodeMCU CP2102 ESP-12E 4M Bytes Internet of Things WiFi Development Board Serial Wireless Module for Arduino IDE Micropython (5PCS) : Electronics
TUTORIAL: Quickly getting started with NodeMCU / ESP8266 12E - In 7 mins! Beginner Friendly! Arduino - YouTube
Let's Start with ESP-NOW (ESP8266 NodeMCU with Arduino IDE)