The Redwoods begin the season on Oct. 17 against the New York Sentinels in the four-team UFL. Las Vegas and Orlando also have teams.
Fullback Ayanbadejo played nine seasons in the NFL, but not since 2006, and won a Super Bowl with Baltimore. His contract was terminated by the Bears in 2007 after he completed a four-game suspension for violating the league's policy on anabolic steroids and related substances.
Sams, a wide receiver, spent parts of five seasons in the NFL, mostly as a kick returner.
"There is a tremendous amount of raw talent on this California squad that just needs some finessing and the opportunity to show their abilities," said Redwoods coach Dennis Green. "I am anxious to begin training camp in Casa Grande in September where we can really get back to the basics of playing football and the fundamentals of what it takes to win ballgames."
In all, the Redwoods signed 15 offensive players, 15 on defense and one special-teamer.