Hawthorne, California. From early 1950's (as UNGAR) into the late 1970's, Eldon was a leading manufacturer of plastic 'Selectronic' slot car sets. Also famous for 'Skee-Ball' and 'Bowl-A-Matic' games. Toys also included a wide variety of inventive plastic cars, trucks, toys boats and Billy Blastoff figures.
They were aquired by Cox Industries in 1979.
What's it worth? Take a look at this Eldon price guide: sold listings for a value indication.