Unreal Marketplace has announced their free items for May 2019:
Chameleon Post Process - SumFX
An advanced post processing Blueprint actor with 70 customizable and combinable effects
Houseplant Pack - Interior and Exterior Plants - IanRoach
An assortment of houseplants and customizable planters
HQ Residential House - NOTLonely
A collection of over 200 ready to use objects and a lit, assembled demo home
Jetpack Animation Set - iamjohngalt75
A set with over 726 animations for a character interactions with a jetpack and weapons
Modular RPG Heroes Polyart - Dungeon Mason
A modular RPG pack with various weapon stances and animations
Particle Text - Killer Refresh Entertainment
A particle system that outputs user-defined text
Platformer Starter Pack - Platfunner
A collection of assets to build and create 2D or 3D platformers
Retro 8Bit Sounds - Gamemaster Audio
1001 retro game sound effects
Urban Material Pack - Plan B Studios
A pack of 41 different urban-themed PBR Materials.
User Interface Kit - Christianos Philippos
A collection of widgets, icons and UI elements
New Permanently Free Content:
Free Furniture Pack - Next Level 3D
A collection of 37 different high quality pieces of furniture
M5 VFX Vol2. Fire and Flames - JeongukChoi
Create various kinds of fire, such as shaking candles, bonfires, fire, flames, and explosions