Gosh, this must be some special grass!  Whatever you do is going to leave
some kind of mark. Anti-gravity moorings cost more than $5....My initial
idea was to broaden the base as much as possible to give stability without
serious stakes. A wooden or tubular tripod with cross-bracing ought to be
cheap enough. If you made it about 1 metre high and spread the ground
contact points about two metres apart you ought to be getting near to the
kind of stability you need for a lightweight human-sized figure. A decent
sized tent peg through each foot of the tripod would do wonders if there was
any wind, and would not make a significant hole in the LAWN. I don't know
how long the figure would have to remain on site, but a lightweight tripod
of this kind could be moved around and re-pegged to prevent yellowing of the
grass under the tripod feet.

I thought about other ways of spreading the load, car inner-tubes and so on.
Everything else I started to come up with began to get complex and
expensive. Three tent pegs, each about the diameter of a pencil, and of a
good length so the pegs didn't tear out of the grass will give a hell of a
good hold if the ground is good, and the angles and leverage of the tripod
is right .
You could ease the stress on the system still further if you made the stem
that carries the scarecrow flexible enough to bend a little in high gusts of
wind.

Still, I'm not meeting your design brief, but briefs can be altered if
people can be persuaded of the difference between a darn great stake and
three tent pegs..........

Alternatives......   are there existing supports to use?  Lash the scarecrow
to the statue of Ned Kelly/Victoria/Gum-tree.
Can you run ropes in from surrounding buildings/lamp-posts/statues of et.c?
If you could achieve this then you could suspend the scarecrow above the
grass.
Make the scarecrow really light..balloons? innertubes?inflated plastic bags?
and fill its boots with sand. Shop display manequins have nice broad heavy
bases, they get chucked out when the body in question goes out of
fashion...use the figure or just the base...make sure it gets moved around
so the grass does not die. Other bases of this kind spring to
mind...portable net-ball posts have some really heavy cast-iron kit at the
bottom [well, here in England they do] could you borrow something like that
from the local schools?  A lorry wheel on its side with a pipe wedged or
welded in would make a ripper..cheap enough from the local scrapyard, and a
bit of friendly persuasion might get the pipe to support the figure welded
in for free.You could leave the tyre on maybe? A car wheel and tyre might be
good enough if the figure was light enough, and it would be a sight easier
to shift around too.
Arr..Heritage... what about a nice authentic cartwheel to make a base?
Whack in a really massive stake and tell them it is just right for the
'Maypole Experience'.
And lastly... what could you push out onto the lawn that wouldn't look out
of place, and would be acceptable? A cart would make a solid platform to
erect a figure on...anything with wheels could be used I guess... a plough,
a tractor, a very patient horse [spot the wheels].
What about a wicker figure? That would be reaaly light..but would need a
deal of skill....

Sorry, I've run on a bit. Come back if you think any of these ideas are
worth thinking about; or if you think I need a clearer view of what you are
trying to achieve to help me come up with more focussed ideas.

Silas.<[log in to unmask]>