Here are some free stories available in both English and Thai.
Busy Ants - English | Thai
Lost and Found - English | Thai
My Friends - English & Thai
The Greedy Mouse - English & Thai
How the Lion Got his Mane - English & Thai
My Fish! No, my Fish! - English & Thai
Too Big! Too Small - English & Thai
More Stories from StoryWeaver - HERE
These stories are in Thai, but if you click on the story title (not Quick View) you can open versions in other languages too.
More Stories with the Let's Read app - HERE
More Stories from Rivet - This is an excellent resource, but they are not parallel books. However, there is a built in one-click dictionary and you can sort them by difficulty.
Short Audio Books on YouTube
These books are read in both languages.