Not many, here are the options:
trets
erst
rest
rets
sett
stet
test
tets
tres
tret
zest
ers
res
ret
ser
set
tet
er
es
et
re
AerobesAerobebearsboarsbeersrobes
Words that can be made using some of the letters from z, s, s, r, i, and e include sizers, rises, sires, sizer, and sizes. Additional words are sis, sire, ire, and is.
Some words that can be made out of the letters TATERSN:tensenttanstaretatersatstentteartreattenssanenestrattastesear
reals, rales, slare, laser
A L R S E T:AlertsAltersSalterSlaterStaler
dregs
adventures
Six letter words that can be made with the letters 'reblmoarts' are:ablestalmostamblerarrestbarestbarrelbarterbasterboaterbreastmarblemasterMerlotmolestmoralemorselmortalmortaroblateramblerarestresortroamerrostersombersorbetsorrelsorterstablestreamstrobetremor
Scrabble words: E I S S R R B:6 letters:BirsesBriersRisers5 letters:BiersBirrsBirseBisesBrierBriesRibesRiserRisesSires4 letters:BierBirrBiseBrieBrisErrsIresRebsReisRibsRiseSeisSersSibsSireSirsSris3 letters:BisBrrErrErsEssIreRebReiResRibSeiSirSibSirSisSri
Some words that can be made from those letters are: "her", "his", "lie", "isle", "rise", "sire", "hire".
rebars
err, seer, gee