Some of the more recent resources that I think for middle school varsity and non-varsity are pretty good (and you can look at the preview of the score online!) are:

Texas Prep Level 1
https://www.jwpepper.com/texas-prep-level-i-11558137/p
https://www.jwpepper.com/texas-prep-level-i-vol-2-11590068/p

Texas Prep Level 2
https://www.jwpepper.com/texas-prep-level-ii-11558138/p

Sight Reading Exercises
https://www.jwpepper.com/sight-reading-exercises-11425232/p

The Tyler Arcari looks like it could be good as well; I just have not used it yet.

Some older ones that I have used that are also pretty good are:

Jerry West Sight Reading Books for Band (Careful, there are some that are harder than level 2)

101 Rhythmic Rest Patterns
https://www.jwpepper.com/101-rhythmic-rest-patterns-4509725/p

Best Wishes!